Cool. So what I've found useful is to spend a little bit of time upfront to decide how you want to do your partitions, and what file systems. So, for example, I don't care about backing up projects (yay git) and their build artifacts, don't care about .cache, but do want backups of .config and my steam library. I use btrfs for snapshots, and btrfs send that to my NAS, but obviously a lot of stuff can be restored easily so that's bind mounts.

Or use LVM (with or without LUKs) and at least give yourself some wiggle room for later.