A t0 at gun for allies isn't that great of an idea. I mean Ostheer light vehicle play is non existent, so a direct counter to the 222 ready and available at t0 is a bit to much. I understand that OKW has this option, but we must be realistic and see that Axis face way more light armor than the Allies will face from the Axis. Especially with the brits coming.
The point of a T0 AT Gun is so that you have an AT Gun whether you take T1 or T2.