Well, the server will be the thing that accepts uploads and gets the images from wherever they are actually stored (either on disk, in a cloud storage, etc). But maybe the thing you want most atm is a tutorial for how to set up a selfhosted Blossom server?

What I'm really asking would be what people want it to do besides supporting the Blossom protocol. E.g. npub blacklist/whitelist, rate limiting, filetype filters, account system & payments, etc. 

 Cashu payments would be ideal.

I’ll have to read more about the protocol to add other things.