I know at least S3 is popular, and their API is implemented by many other providers
File storage is now abstracted and both local files and S3 are now supported
now in use on b.tide.tk
Still using a fork of rusoto-credential until this PR gets merged
But they don't seem to have updated anything since April 2022, not sure if this is the library to use going forward but the rest of them seem to be "experimental"
either way, works for now