I didn’t say you couldn’t or you shouldn’t - all I am saying that if you tinker enough then it is going to be unstable - that goes for any system - with macOS as an exception where we all know why 
If you try to install a theme on EndeavourOS from KDE store - one of those fancy macOS themes then you will get the exact same issues as any other system using a KDE desktop. Again maybe Neon is an exception here.
Yea borked more than few Linux and Windows installs over the years.
Garuda ultimate is ugh…do you think your roommate will need all the apps that ultimate offers?
No, but it’s preferable to having to buildup EOS and teach him. Especially since I’ve still got so much to learn myself.
basic 101 linux, not every distibution or os are Rock solid. and there is also a difference of things when things dont work.
Endeavouros has a solid base learn from, is mayby not Newbie proof.
Most time is always linux how far they wil learn also.
external tools can be crappy on a point not always 