Apart from the personal data in home directory, personally, I would backup:
the dot files and dot folders under home directory
/etc
I would then restore what I need from these on a per case basis.
Edit: you could also make a package list of all the packages explicitly installed and reinstall them all at once:
2.5-2.6 https://wiki.archlinux.org/title/Pacman/Tips_and_tricks#List_of_installed_packages