Dont own a steam deck, but at a guess you might be able to add the terminal lines to change shells to you bashrc, should load it in on first start and then fish will be default from then on.

I’ve been doing tags on files in a single folder. Ever note in the same folder. Notes get catagory tags. Doesnt match a catagory? New catagory. Its very simple and doesnt side track me with organisation as much