I have a proof of concept developed in Coracle, files are uploaded to multiple hosts at once via NIP96 and nip94 events are generated for each file with all URLs. We are working in parallel with Fishcake to standardize the communication between hosts, allowing more advanced features in the future.

If you want to test what I say clone the NIP96 branch of Coracle, made by me.

On the other hand, congratulations nostr.build 😀, I will soon have to make a decision about it (paid accounts), NIP05 services are not expensive, but multimedia hosting is very expensive!!