sudo softwareupdate -i -a --restart

I look like a fat version of the bottom left but use Ubuntu

I’ve never used systemd to shut down

Sudo shutdown -h now works on the Mac

I’ve run most non KDE distros now I just install Debian or Ubuntu depending on the computer

If the digital download comes with a key can’t you just save it on an external HD when you download it?

I tend not to recommended Linux to anyone because I always end up their tech support.