Profile of nee

Give them to Volks to Obers. Making a new unit in the one faction with the most non-doc combat squads is just bloating the game.

Volksblob with 1x schreck each was powerful, but if it was an AT rifle instead then that would reintroduce the AT role for them without the high firepower. It also gives them 1x slot to pick shit up. Obers can have the 1x schreck if you really so desperate for a rocket launcher that's not on wheels.

My opinions on specific healing mechanics:

Some healing mechanisms are stronger than others, but I do kind of want to maintain asymmetrical design. That said, some of the certainly need improvements, and I believe they can be improved without the need to simply copy other factions'.

Considering Ostheer squads being smaller and can only heal other squads, AND being vet1 requirements, I think they should be tweaked so that they can either heal themselves (you just select the squad), and/or heal faster. Being smaller squads that need to maintain squad preservation, this might help.

OKW I'm a bit ambivalent- they're passive and automatic so there's no micromanagement burden. Someone said their healing rate wasn't increased since last patch so that may be the issue at hand more than anything else.
If I were to change it, I'd just make the healing a munitions cost aura healing, similar to the Brits' medstation in CoH1. For better or worse, this can mean removing the medics upgrade.
If we're to have HQ include healing, then perhaps this idea could be used instead, so OKW gets both but T2 still needs the sidetech while the HQ is a timed munitions alternative.

USF Ambulance is fine, it was certainly crap before you can toggle to immobilize. Being mobile aura healing option that is only 10 fuel AND a T0 unit, having paper thin armour is fair tradeoff.

UKF's Tommy healing is fine as well, the only issue I have is that the radius seems too small, a few squads in formation will tend to have some healing while others don't even if they looked really clumped together.

Soviets' healing is fine as well, while it's only at HQ, they don't have forward retreat so any retreating guys will inevitably get healed by a T0 upgrade that costs only manpower, and Soviet squads are larger, plus one of the best halftracks in the game. If they're to be improved, I say just add more medics.

Man, this game and Relic. And they're no only abandoning this game, but high change DoW3 will have this problem too.

If you go Med HQ, you will be better at preserving your units and field presence. However, you have literally no good AT units and no vehicles field presence...
If you go Mec HQ, you will have a chance in dictating the LVs warfare: early Luchs, Puma and Stuka.

I believe the infantry support/ light vehicle warfare already happens with current OKW setup. In fact the original OKW makeup, where Volksgrenadiers can upgrade to panzerschrecks, worked too well that they gave it to Sturmpioniers as a nerf; prior to the current design, OKW were basically the blobschrecks of the game; now USF with their Riflemen blobs are the new A-move norm.
I don't see how giving Sturmpioniers flamers and Obersoldaten panzerschrecks to mimic Pioniers and Panzergrenadiers respectively changes anything. Ostheer's unit design and teching work well because you got good capabilities balanced out by small squads. What you have here are good capabilities but no longer with the fragile squad drawback. Specifically, Panzergrenadiers are not backed up by5-man squad mainline infantry; Osttruppen squads are great help due to their larger squad size. Now imagine if Ostheer had 5-man Grenadiers. Got it? Good, because I just demonstrated to you that you might as well just change Ostheer itself to get your ideal faction, AND also demonstrated how much more (over)powerful they would be under this change.

OK, now imagine the unit compositions inside all tech structures. Just imagine what units are inside different tech trucks... Seems similar to something?... That's it! It seems similar to the Ostheer's unit compositions in tech buildings!
And that, my friend, is why I named it the second Ostheer.

3. Volksgrenadiers: Replace 2 StG44s package LMG 42 or 2 G43s.‎

And here we delve into the problems with changing OKW units and affecting their doctrines: This change makes Volks the same as Panzerfusiliers from Breakthrough Doctrine. Also by proxy, the change for Obersolaten as AT infantry is countered by their upgrade to infrared StG44s via Spec Ops doctrine. The OKW commander design alone makes turning OKW into Ostheer clone nearly impossible to work.
If you want a closer Ostheer infantry style meta you can just give 2x Schecks to Volks as T2 unlock at like 120-150 munitions, have it compete with literally every munitions upgrade/ ability, locks out the StG44 upgrade and allow a more versatile Volks build order. There, we just turned Volks into Grenadiers + Panzergrenadiers without reshuffling anything. If you want a Grenadiers and Panzergrenadiers setup, you merely train 2x Volks squads and give them different upgrades. Seeing as you're going to be needing multiple Volks squads since the alternative is T4 or a more expensive builder unit, you might as well just give the versatile options to the most common OKW squad in the game.
In regards to Obersoldaten, like any squad in the current game version they will spawn out of their respective tier building. This means that at T2 (and presumably at lowered cost) they can pop up at the front lines wherever T2 is set up, presenting a big problem to balance. At least through T4, their arrival is rather late to the party, and their high cost prohibits them from being a common sight in any match.
Which leads me to my last (or actually first) point: the biggest difference OKW's tech structure from Ostheer's is the HQ trucks themselves, which despite being the primary foundation of the faction design and thus their teching structure, you deliberately avoid to address. Unlike Ostheer, a major strategic factor in OKW's success/ failure is preserving OKW trucks. Here there are two linked yet separate issues: first, OKW trucks can and are encouraged to be deployed outside the HQ sector to provide close benefits to your army- by doing so they risk being destroyed and therefore lost to enemy action, which deprives the player from building units.

Given how the OKW is designed and what it's intended design goals are, making he units operate like Ostheer won't work. This ultimately is what makes making them a Ostheer clone a dumb idea. If you want to solve this problem you simply have to think outside the proverbial design bubbles that most Ostheer fans need to get out of.

I didn't say Ostheer is the problem. Ostheer's unit compositions in tiers/tech structures are very much standard (With the exception of the lack of light vehicles). The problem here is actually OKW in their unit compositions.

No, the problem is you want OKW to be like Ostheer, rather than just making Ostheer be the sort of Axis faction you desire. That is either the problem with the Axis faction, or your problem with how they work and how you want them to. OKW design might not be perfect or god forbid non-standard, but that's a fundamental difference to playing that faction that not only I like about it, but sort of the reason why it was made and sold to players like me in the first place- it's not like Ostheer.

The main reason why I propose these changes is because I want OKW to have a more standard and less risky teching just by changing some role and unit positions in the tiers/tech buildings. Right now, they seems to be facing the highest risk and being most vulnerable when teching up, in my opinion.‎

And I am pretty sure that I'm not the only one that doesn't like the idea of buying an Axis faction only to have it changed to work just like another Axis faction. I believe the entire (selling) point of OKW is to not be like Ostheer.

What you want is to make an Ostheer that does not have fragile squads and does not lack light tanks. Seeing as OKW has both of what you want and just lack the tech design of the former, it's no surprise what you're trying to do.

You're also not going to solve the teching issue assuming it is an issue, by simply making the units swapped about an changed to operate like Ostheer equivalents. That's like saying your truck's engine problems will be solved if only you made it look and sound like a racecar.
While I agree that their teching structure has highest risk and vulnerabilities relative to other factions, I believe that is the point of HQ trucks. If you want to reduce risk and vulnerabilities, then perhaps the better way is to simply buff undeployed HQ trucks?