The 1.9.0.5 lists "Added: Full steering wheel support (including gas, brake, clutch, and shifting stick)" in the changelog. Sadly with the Moza R3 wheel base this feature does not work. The wheel base and pedals are seen as 4 different dives, with none of those 4 devises allowing you to map any axis (steering, pedals..) to any action. Also none of those devises "just work" for any axis. So the Moza R3 end up not usable in Arma Reforger.
1.9.0.9 Update:
Now there is a second devise selector for the FFB, and a joystick inputs tab. The tab is semibroken right now. For some values you have to assign both inverting and a 90-100% negative offset. I also still couldn't make my pedal shifters to work properly, I've only managed to get shifting up to work, bit the shifting down pedal for some reason was also only able to shift up. The FFB itself is buggy and very noisy. For it to become adequately good it has to provide information about the front wheels grip and overall state, while not creating to much noise with road effects.

Surprisingly! The "Added: Force feedback for steering wheel" does just work when FFB Device ID 0 is selected. So when driving with WASD the force feedback does feedback and force quite some into the wheel base.
System info:
OS: openSUSE Tumbleweed (Linux 7.2.4)
Proton: 10.x-11.x (versions tested)
P.S.
Yes, racing seems like Assetto Corsa Competizione do "just work" on this system and with this wheel setup.