For files I use syncthing (also for music/photos/notes/etc... syncing files is IMHO the way to go wherever applicable).

For sending links to my PC (eg. articles linked from podcasts' notes) I used to rely on firefox sync, but I'm starting to distance myself from Mozilla so I am gonna experiment with wallabang.

For sending small notes to myself (stuff that I want to sort or act upon when I get to my PC), I'm using signal's "note to self" but I'm investigating alternatives because signal doesn't mark such messages as unread and so sometimes I forget I've sent some.