As someone pointed out on the comment, one of the reason is Money, the other one is safety and security based on Vehicle manufacturer claim.

Yet, nobody can stop you to sniff and monitor your own car CAN/OBD2 interface using as simple as cheap microcontroller and compatible OBD2 interface kit (e.g CAN Transceiver/Controller kit).

EDIT: So far this curated list helpful to me for CAN bus based protocol.

For games, you’d rather use game repacks as they sometime provide smaller package for downloading. The most common one are dodi, fitgirls, though other repacker like el amigos, KaOs krew, Mr Dj also available. If you don’t mind ddl, cs-rin.ru and torrminatorr also available.

Avoid IGG-Games they have shady history in case you use public tracker.

remember rtfm! Megathread, wiki, fmhy are available so you can browse easier as provided by the community.

From my experience, I can install several repack without any issues on my Mint install (using wine). If you overwhelmed, the easiest way is to add the .exe of your game as non-steam game through the steam and the proton will handle the rest assuming you won’t find dependency issues, if you stumble across problem try to search protondb for solution.

Personally I run my games with wine because I couldn’t figure out how to make use of bottles and lutris (ye I’m weird).

EDIT: Also you can run your modded games on Linux, so far I have tried modded nfs mw (2005) with hard+, underground2, and new vegas, they are works like on Windows.

If shit happen, rtfm. gl op on your journey!