It's the M42 AT gun of OKW, I guess.
Yeah or the 250 Half-track of the Wehrmacht but still, the Wehr have default access to the 251 HF while the Soviets have the better ZiS 3, the M42 should have the abilities of the raketen to retreat and garrison buildings to make it gameplay practical for it's size if you ask me, Relic should have added the ZiS 2 57mm AT gun instead of it if not then. But the MG34 being a default unit (that's lacking) now doesn't make sense and has no alternatives, even as a doctrine unit it was the cheapest of them all the underperforming and you needed at least 2 or 3 in order for them to be effective while now... It's still underperforming compared to the other MGs (Well, except for the Maxim, when not garrisoned) and coming too late compared to the best 2 MGs in the game, those being the MG42 and Vickers, well, the Vickers being arguably the second best here because of it's price and lack of the MG42 and MG34's vet 1 penetration abilities, plus it's range doesn't really help it that much on urban maps with lots of houses.
P.S.
No, the Flak Half-track is bugged and costs fuel so does not count as an alternative, even my grandmother with an AT rifle could do better.
Edit:
The 42 had higher RoF as a result of simplification of the gun, in fact in case of smgs and most hmgs too, high RoF is an disadvantage. Germans had many other mgs that had even higher RoF but these were nearly impossible to effectively use on tripod and used way too much ammo. Mg-34 was considered better in every way by german soldiers, with the lower RoF (and thus also better accurancy and effective range) being one of most important reasons. It was also impossible to mount mg-42 as tank mg.
Another example is M3 smg vs the thompson, the first one has cheap and simple construction with cheap light bolt, cousing the gun to shoot very rapidly. The thompson had heavy bolt, especially designed to maximally lower the RoF, so that soldier could shoot longer without changing the magazine and also much more accurate. It was easier to shoot with short series, too. That's why all well trained soldiers got the tompson, while the m3 was a cheap smg for tank crews and engineers ment only for self defence. The fun fact is that soviets had no idea how to build a slow-shooting smg, so they just gave PPSh larger magazine, still the gun needed a lot of training from the soldier to be able to hit target reliably, much more than any other smg.
So yeah, the only advantage of the mg-42 was that it could be produced much cheaper, without it germans wouldn't be able to fulfill their machinegun production plans. Also, it is not shown in game and probably is never going to be.
Slight correction, the soviets COPIED it from a finish weapon, which's name I forgot, and even copied their own hand-held weapon from you guys, that being the PTRS and PDRS, hell they didn't even have any kind of rocket propelled AT weapon besides the few lend-lease bazookas they got, could have copied that as well and called it something else, might have saved a great deal of Soviet lives but no, we no copy Amerikanski technology tovarish, we strong independent and proud Soviet people that don't need no imperialist and capitalist technology to help us in our glorious struggle in the great patriotic war!
Absolute, pure, fucking, bullshit.
Edit 2:
I just wanted to add to your production notes of the MG42, so yeah that's why the MG34 was kept in production and service until the end of the war along with the 42 even when it was more complex and more expensive to manufacture, plus Germany being on the defensive mostly after 43' the MG42 felt right at home in the hands of defending German soldiers suppressing Soviets and Allied infantry units, the fear factor was so great that Allied troops called it "Hitler's buzzsaw" even, not kidding.
There are probably a plenty more documentaries that can add to all we've said here that's probably not even half of both MG's stories.