If your monitor/docking station/adapter and the computer support the DP Alternate mode, then you should use that, it should be supported directly by the kernel. Problems may occur if the port is connected to the dedicated graphics and you use the internal graphics card. In my experience it worked perfectly so I do not know any good troubleshooting steps.

It is not required for the displayport alternate mode of usb-c.

It is an alternative with limited performance that is built on top of usb and does not require hardware support on the PC side.

I’d guess retro arch is running as a Wayland client. Try to force it to use Xorg / XWayland or read this https://github.com/ValveSoftware/steam-for-linux/issues/6148

There is arcan, I have never tried it, though. https://arcan-fe.com/about/

So, they are talking about a bootkit embedding itself into the uefi firmware, then the graphics show a malicious bootloader that resides in the EFI partition that can be removed by formatting.

Elgato does not want Linux users: https://github.com/tolga9009/elgato-gchd/issues/15#issuecomment-610984742

I mean the exact same 2.8GB file, with the exact same USB-C stick took FU***** 3 seconds on Linux !!

For that test you should run sync afterwards to make sure the file was really written and is not waiting in a cache.

It is possible to format removable drives without root access through udisks2, e.g with gnome-disks or KDE ISO image writer.

Sorry, I have no idea.

The relevant polkit policies should be defined here: https://github.com/systemd/systemd/blob/main/src/login/org.freedesktop.login1.policy

Disabling is done with some rules like this: https://bbs.archlinux.org/viewtopic.php?id=152565

polkit.addRule(function(action, subject) {
  if (action.id.indexOf("org.freedesktop.login1.power-off") == 0) {
    return polkit.Result.AUTH_ADMIN;
  }
});

Some other examples: https://gist.github.com/grawity/3886114

Is it common for cups to run as root? It should have its own user, but that is still not good.

Hmm, never had cups-browsed enabled as I do not need network printing with LDAP or legacy cups. Discovery using DNS-SD/mDNS and driverless printing work perfectly fine without it.

I am not sure if the driverless discovery ever can generate a PPD with arbitrary commands.

For Linux maybe timekpr-next and some custom scripts to sync the time with the time limit server?

ReactOS is probably a good indicator how far you can get with some limited generic drivers.