`/usr/local` is writeable so no change there, that should work fine. I keep a container as my "day to day" linux and just have my terminal autolaunch into mine. You can use any distro's container for this so it's personal preference.

I'm using Prompt, it's a new terminal designed to make the toolbox/distrobox flow much nicer: https://gitlab.gnome.org/chergert/prompt

It's still relatively new so it isn't on flathub yet but it makes everything mostly seamless.