It depends on how you install stuff. Games on Steam or downloaded from online from places like itch.io can be put on any drive without issue.
In terms of software though, native packages (deb, rpm) are gonna want to put files in various system folders, so it’s pretty much impossible to get those off your os drive.
Other packaging solutions can help with this though. Appimages can be put anywhere, nix let’s you install to another drive, same with flatpak.
And if you’re savvy, you could use docker to install system packages on other drives, although I wouldn’t recommend it.
Csgo and 2 have a “trust” system to keep track of player behavior and put you in games with others of similar trust value. So if you get reported often or have a history of bad behavior, you’re more likely to be put in games with other bad actors, and vice versa. Idk how effective it is though.
Honestly there isn’t a great solution, which is kind of why I avoid competitive multiplayer games. Even kernel level anticheats can be circumvented.
The nice thing about vac is that theres pretty much no false positives. And valve will occasionally update it, catching a ton of cheaters off guard and getting them banned.