I use both Seafile and Syncthing for various things.

I've managed to setup seafile ok behind traefik as a reverse proxy. Seafile has a basic web front end and allows you to integrate with Collabora for editing open document files. Its fine to just shut down the docker and copy the database I've found for backup. Or you can copy the files themselves, if you don't care about the change history (which I don't). I have as script to do this each night. Seafood isn't too hefty and runs well on an RPi, even the collabora integration does.

Syncthing is a really good piece of software and I use this to share files from my RPi to my phone, but bare in mind by default its send&receive both sides so its not suitable for backups in that state.

Let me know if you want to know more.

I use tailscale + tunneling, so rProxy shouldn't be an issue. I already use Syncthing but looking something I can use to share links to file and access from public in general. Seafile or FileRun seems to be good in my case.

I too use Synology Drive for the stuff I want to keep to myself. Which is basically everything. :)

Seems like the only option for something that can be on a multipurpose PC.

Set up your folders, get your devices synced, and it pretty much sorts itself from there.

I've had minor temporary issues with Syncthing, nothing that hasn't been fixed quickly (and have yet to had them happen again).

Great for music and photos between PC and phone and for transfers between music production PC and gaming PC. Better than Dropbox and GDrive for most purposes (lacking support for online link sharing, which isn't very important)