When playing with German vehicles in War Thunder I use the 2.8 cm sPzB 41 light anti-tank gun (or a heavy anti-tank rifle) mounted on SdKfz 221 armored car, which is among the most light weapon systems one can operate with in the game.
For more info , read via https://en.wikipedia.org/wiki/2.8_cm_sPzB_41
Thanks for reading , keep on gaming :)