Hi - I suspect the answer to this is that it will work just fine but I just want to see of there are any gotchas.
Currently I use CentOS 7 with TeXLive installed in /usr/local/texlive
That directory is owned by user:group texlive:texlive so I just log in as that user to update or install the occasional package that isn't part of texlive.
I'm planning to build a new system as CentOS is going away. I'll probably go something Debian based but haven't decided.
Anyway my plan is on new system to create user:group texlive:texlive with identical UID/GID and just rsync my install on over also using /usr/local/texlive and after the rsync just run tlmgr to update it.
As long as the new system is also x86_64 linux and I make sure to set up /usr/local/texlive/2021/bin/x86_64-linux at the beginning of my path, that should continue to work flawlessly?
I can't think of why it wouldn't work, just sometimes there are things I can't think of so if there are any gotchas I'd like to hear them. Just makes more sense than a fresh install that takes hours and where I then also have to set up my font maps again etc. for local installed fonts.