Moon+ has what you’re looking for. Syncs to box, Dropbox, gdrive and webdav. And can download from opds libraries like calibre if you selfhost your epubs.

I do like copyparty, not sure about gitgub, though.

I was about to start my lucrative career in DDoS but, alas, I’ve been thwarted.

1984.hosting has a great free tier, and I’ve never had an issue in 7+ years

Where’s the link? I’ll play along!