Last week Swyx nerd-sniped me into building an Open-source Dropbox.

Here is Locker: An Open-source Google Drive/box/Dropbox alternative - Provider agnostic (S3, R2, vercel blob, local) - BYOB (Bring your own bucket) - Virtual file system - QMD Search plugin

Locker is designed to sit on top of your bucket, so you can use whatever provider you like best (Or just use a local disk)

BOYB means you don't have to self-host to use your own bucket, just add your keys via the hosted UI, and you're good to go

Locker itself can act as its own S3 bucket, meaning you can generate Locker keys and use them in other applications to have data saved directly to your locker.