but... if you use unprivileged user namespaces, tmux isn't a very good use, because then you can't use any suid programs like su, sudo, doas, pkexec, fusermount

but... if you use unprivileged user namespaces, tmux isn't a very good use, because then you can't use any suid programs like su, sudo, doas, pkexec, fusermount, mount (user), etc.