I switch back and forth between bazzite and bluefin quite often

on these and other immutable distributions, /usr is read-only, and the recommended is to use installation methods that write to your HOME (or to /var which is where docker and flatpak --system save files)

i really should muck about with container-based development flows

my current preference is flatpak, then whatever per-language package tooling (e.g. cargo for tools written in Rust, npm with a custom HOME prefix for tools written in Node.js, uv for Python projects, etc) when there's no flatpak, then homebrew, then rpm-ostree as a last resort

for editing files in /etc my recommendation would be to set the EDITOR environment variable to point at whatever you like, installed however you like, and edit with sudoedit /etc/fstab, because then your editor is not running with root permissions

you could also point EDITOR at a custom script that mounts the target file into a container running your desired editor