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Are you talking about 2FA login for your own user account or U2F/PIV/WebAuthn in your browser? The latter seems to work out of the box on any non-snap or flatpak browser, but the former needs a bit more setup as that is not a standard feature in Ubuntu yet. I recommend using ykman and yubico-piv-tool for configuring yubikeys in linux, but Yubico also provides a GUI application on their website
Wait till you see public companies
If you’re talking about the Temp folder, the equivalent to that in Linux is /tmp/ which behaves exactly like you described. ~/.cache is more like a general directory for any cache that programs might wanna keep around for longer than a single boot. I’m not aware of special directories like this on Windows. From what I’ve seen, most programs on Windows tend to keep it in AppData alongside non-cache files
If you’re a gun enthusiast or just would like to mess around with some of the most detailed weapons VR has to offer, I strongly recommend trying out H3VR (Hotdogs, Horseshoes and Hand Grenades is the full name I believe). Yes, it has never been on sale since it came out, but it’s 100% worth the 20 bucks they’re asking for. There’s also an awesome multi-player mod for it called H3MP, as well as heaps of other content mods.