AC works fine with a very small amount of effort for me. I found https://gist.github.com/tim-gromeyer/2fbce4609f7d6d330e81504bcea70546 to be helpful.
Dirt3 is going to be difficult. There was a lul in game development for steam based games around this time. Ferral was trying to make native ports (dirt rally) and also trying to make working proton ports but it was very early on in that effort. It resulted in a lot of games which "worked" when they were released with a bunch of hacks to get them working, followed by zero maintenance releases causing all those hacks to fail when Linux and supporting libraries were updated. No one was interested in fixing dependencies so some of these ports are unplayable now.
If you are interested in the dirt series and rally racing Dirt Rally 2.0 is worth the money in my opinion and works very well on linux.
My experience with arcade style games such as Forza Horizon 4 is that they don't handle input devices very well. Even in windows I believe you need software which emulates a G29 or something to get real sim racing hardware like separate wheel+pedal+handbrake usb devices working. I've had issues in carx drift that were similar but those were solvable.
My biggest trouble has been pedal support as my pedals are a standalone usb device with only 3 axes. protopedal and xboxdrv both can help workaround these.
Wheel support is hit or miss and you should be very careful what you buy right now. Have a look at the oversteer readme. There is a list of known drivers for various wheels. The logitec wheels, with the exception of their new DD wheel, are all in-tree and well supported without extra work. Other things like certain Fanatec and Thrustmaster models have their own community based reverse engineered drivers provided as loadable modules. And some things like higher end hardware, simucube, moza, etc. have zero support and FFB will not work.
My last piece of advice is: use gamescope. Especially if you are on wayland. It makes everything a million times easier and more stable.
Feel free to ask questions, most days I feel like playing with games to get them running on Linux is my actual hobby, and not playing the games.... =]

Does this mean federation is turned back on? I just tried to comment on a post on lemmy.ml and things appear to still not be syncing.