Profile of nee

How about PTRS for Penals? Two of them per upgrade so they can't pickup stuff? Gives them infantry AI without going doctrinal, and Guards would be more versatile because of grenade and DP-28s. That way you can tag team with Conscripts' snare and Penals' light AT damage, until T2 or vehicles arrive.

They're in a good spot, if anything it's their high manpower cost that makes them an unsuitable altnerative to just using Penals.

I'd also go for a sprint/ Urrah! ability, but besides balance, Shocks are found in Counterattack Tactics which feature the Motherland ability which does the same thing. They also have smoke grenades to avoid suppression.

Reduce auto-fire range like the other artillery units? At least that way you can shit all over the map but only if you use barrage ability.

I would personally say no in regards to Panzergrenadiers.
Yes it does improve their firepower but you've also got another 45 munitions invested into a 4-man squad whose main job is infantry AT. It's already a big loss when you lose 120 munitions worth due to potential squad wipe, I'd rather just give it to a Grenadier squad rather than concentrate all 165 munitions into a single squad. Given the limited munitions to go around every match, IMO it's better served spread out to more squads.

That's not to say I never tried it nor always seen a negative outcome, but from a limited economic perspective, G43s on Panzergrenadiers is hardly priority.

[OST] Elite Infantry Doctrine
0 CP - Elite squad re-oganization (Passive/ 5th man cost 15 muni to buy)
(After getting Vet 3, Pioneer and Grenadier squad will be able to get a 5th man which is a MP40-equipped NCO that logically spread his men out so they not get clump up in 1 pixel. The squad with the NCO will have passive sprint while out of combat)

1 CP - Jaeger Light Infantry Package (45 Muni)
(Allow Grenadier and Panzer Grenadier squad to equip with 2 G43s, can use stun grenade and interrogation)

3 CP - Deploy a 223 Command Scout car (240 MP and 20 fuel)
(A 223 Command Scout car armed with a pintle mounted Mg42 (the one on Pz4) can buff nearby infantries' rate of fire and can order free Recon with a 90-second recharge)

5 CP - Defenders of the Fatherland (90 muni, lasts 60 seconds)
(All infantry squads now gain Defensive bonus while in cover. They are harder to be hit and fire faster)

7 CP - Deploy a 15cm Nebelwerfer 41 (340 MP and 40 fuel)
(Can fire a barrage of HE rockets that deal high damage against emplacements, ambient buildings and infantries)

First ability seems useless, as it's a munitions upgrade but only actually comes around if your squad ever gets to vet3. Adding additional men also sort of knocks the balance design off the rails. I would instead make it a free passive, and instead of a 5th guy, one of the existing squad guys is replaced by the NCO.
However, what this ability ultimately does is give passive sprint, of which Ostheer already has two movement-speed abilities, namely Sprint and Tactical Movement. If you want the Elite Infantry vibe, I'd just make this a timed ability where squads get increased XP boost; some intel bulletins grant a passive XP boost, this ability would require munitions, and a time window to capitalize. It also means you can apply this to vehicles as well. It would be far less OP compared to the old Troop Training which granted a flat ~3950 XP to instantly make a squad vet3; you'd still have to make the squad fight and get/ receive damage.

The scout car idea is nice, but as a light vehicle call-in that just buffs nearby infantry like Command Tank, it's not as useful as just getting 222s and rocking the map with them. What this could instead be is an upgrade for your light vehicles (222 and halftrack) called "Command Car Upgrade" or whatever and gain supporting powers that make them relevant late-game, but at the cost of their usual roles, for example the halftrack can no longer reinforce, transport or use flamer, but the replacing power can be powerful enough to warrant investment; in any case you can always just buy another halftrack. Keeps your idea while also making the idea more versatile.

I think the Nebelwerfer idea should use incendiary rockets instead of HE, as Ostheer already has mortar, Panzerwerfer and Brummbar for the anti-fortification roles; there's only one other incendiary ability for Ostheer and that's the Stuka bomber. Incendiary also means it's a lingering damage effect where you might not inflict as much damage, but it does kill nearby infantry trying to repair or reinforce nearby defensive stuff, something OKW has via Walking Stuka, but requires vet4 to unlock and then 100 munitions to use everytime. This unit (or off-0map) however uses it as default attack.

In summary I'd rework it like this:

1- Veteran Squad Leaders: timed ability where units gain increased XP when fighting;
2- Jaeger Package
3- Command Car Upgrade for 222 and 251 halftrack, provides buffs and free recon, but alters unit powers, ie no 2cm or reinforce;
4- Defenders of the Fatherland (unchanged)
5- Nebelwerfer unit or barrage: fires incendiary rockets, effective against everything except vehicles- identical to Walking Stuka's incendiary barrage