This is more or less what I do too. I sync my whole /storage/emulated/0 on Android, which gives me Photos and Downloads etc. to my laptop. I also put Syncthing on an always-on tiny computer at home so if either laptop or phone is off, I can still sync from the other one (so that little home computer is my "cloud", didn't require anything more than plugging in eth and running syncthing).

Syncthing uses "disovery servers" so no need for public IP's or wireguard or anything like that (you can set up your own if you don't trust syncthing https://docs.syncthing.net/users/stdiscosrv.html but they're only used for that discovery part, which is one of the main hurdles when you start thinking about peer-to-peer systems).

(However, I use Fastmail's calendar, for handling invites and since it keeps my subscriptions up-to-date. Considering the move from bitwarden to keepassxc.)