It doesn't seem to exist. I'd like a solution to upload and sync my photos and my KeePass database, but I'm really hesitant to upload personal photos unencrypted to services exposed to the internet. Unfortunately self-hosting a Nextcloud instance on my LAN isn't possible at this moment, but maybe a VPS with a strict firewall and a mesh VPN like Tailscale or Netbird? But honestly I'd rather just pay someone for the trouble.

What do you suggest? Clients need to be FOSS and available on Linux and Android, and on Android they need to be available on F-Droid (thus no proprietary blobs or libraries from Google).