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.

Curtail is a wrapper around tools like pngquant, jpgoptim and oxipng. In lossless mode it optimizes and reorders e.g the compression tables. I know of no tool that does that for video data and I am not even sure that is feasable. Video is not stored as a simple sequence of images.

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

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.

As a CLI there is gifsicle or imagemagick.

As a gui maybe gifcurry, tupitube or some other 2d animation tool https://en.wikipedia.org/wiki/List_of_2D_animation_software