It is. A Möbelwagen was used as a testbed for the 3cm Flakvierling mount. The “proper” Zerstörer 45 doesn’t seem to have existed in steel, because it’s not clear if any of the intended Wirbelwind-style gun shields for the 3cm were ever built.
Given that the chassis now exists in game, it’d be incredibly easy to replace the quad 3cm with a single 3.7cm to create the regular Möbelwagen. It might not be an especially good SPAA (it’d be just a worse Ostwind) but it’s historically important.
A proxi-fuze rocket launcher on a AMX-30 called “Javelot”
Most anti-aircraft systems boil down to two essential ideas: either fire a round out of a gun at a target, the anti-aircraft gun approach, or fire a missile, the surface to air missile. But what about rockets? The French Javelot rocket launcher system would have been an anti-aircraft rocket launcher system installed on an AMX 30 chassis, equipped with a magazine of 64 spin-stabilized rockets, 40mm and around 1 kg each, capable of achieving a speed of up to 1,100 meters per second to an effective range of 1.5 - 2 kilometers with 400 gram warheads. It would fire rockets in salvos of up to 8, 16, or 32 rockets at a time, with the possibility of the magazine being reloaded in 30 seconds - by simply switching out the rocket container. Catulle, a naval variant, also existed.
I use the Type 99 SPH with HE (PF) rounds against air, this Javelot will work well around 7.3 Br range or 7.0. Especially since it has Radar with (PF), it should do it’s job rather effectively.
Anything with 4 guns, 3 guns are needed honestly. The more guns the better it is at shooting down CAS as I have experienced the Whirblewind, much prefer that than the Single barrel Ostwind and Double Barrel Dusters. They do well too, but 4 guns is my preference.