AC works fine just requires a little extra setup, either use this script[0] or use the latest GE-Proton (with a fresh prefix), I recently updated protonfixes to fix a CM/CSP issue. The latter is better as newer Proton has some definite performance improvements.

0: https://github.com/sihawido/assettocorsa-linux-setup

In my (admittedly limited) experience, it does run, even with quite comparable performance, but getting a wheel to interact with the game has been a bit challenging. But this could be resolved with a custom driver for my specific hardware. Using the community standard mod manager seems to resolve the UI jank by completely bypassing it.