I have lots (100s?) of pdfs for ttrpg rules collected over years - storing in folders is enough to separate by game, but fails when a single book is a mix of content - does it go in the adventure, character options or DM folder?
Having a nice UI with tags and searching would help to organise the collection a lot better.
Accessing all of that across any of my devices while the files actually live on my NAS would a be a big improvement - its easy for my laptop & tablet to get out of sync etc
You can store an ssh key in Bitwarden or Keepass(XC) easily enough - Bitearden can certainly be configured as the actual source of your ssh keys with only a tiny bit of config effort