There's a reason why they got rid of panzerchreck upgrade for Volksgrenadiers. How about 2cp Volksgrenadiers 2x Panzerbushe 38 AT Rifle Upgrade. With this, they keep Panzerfaust and Flame grenade ability, while becoming effective against light vehicles but must be massed to take on tanks.
Also instead of teller mines for Sturmpioneers, how about 2cp Riegel Heavy AT Mines, laid by IR Halftracks, Pumas, and Walking Stuka halftracks.
Instead of passive tank awareness, how about tank awareness, in which munitions are spent so all infantry squads can detect enemy vehicles within a radius for the duration of the ability.
The reason they got rid of it was because it was bad game design to have every mainline infantry squad running around with a Panzershreck by default, giving them both decent AI and decent AT. That's no reason to disallow a specialized AT upgrade that ruins AI. Anyway it could be an upgrade for Obers as well or a special AT squad, it doesn't really matter. OKW could just really use a good infantry based heavy AT option an alternative way to counter TD blobs because Rakettens can be very ineffective in some maps (urban) or against an indirect fire heavy enemy. Panzerbuchse just wouldn't cut it.
Riegels could be an option but I don't think anyone would ever use the IR HT or risk the Walking Stuka for that. Perhaps it could also be added to the Kubelwagen to give it some utility beyond the early game.
I specifically mentioned passive tank awareness for diversity because the Elite Armor commander already has an ability to detect all vehicles on the minimap for 50 munis. The range on passive awareness should be just enough to see a vehicle coming and react at the last moment rather than having it light up half the enemy force constantly.