I wouldn’t recommend picsur for scale. It also uses DB backend, and lacks some moderation tools. I used it because it provided a lot of really useful features, such as URL based image conversion. It would be perfect for a self hoster though.

If some of the proposals end up working the way you described in your other post, and have a standard API, then that’s great. It’s almost not “relay hosting the image” in that case though, it’s more like “relay+hosting” configuration.