Okay so I now found S3 Drive, I talked with the dev because you need to agree to some TOS, they provide a subscription model for their coorporation with backblaze. They want to work them over for selfhosted services.

It works very well so far, but in the free version you can only add one Bucket. The app uses rclone as backend and provides a nice UI.

They wrote about it on Reddit if anyone is intrested in asking questions too.

Maybe we could get them on Lemmy too 🐱