I cannot say much about the quality, but I am also testing around with it at the moment. As for the identity control, you may be able to achieve this with a few extra steps, if you set up bucket policies for the credentials. For this, it would be a bit cleaner to move the storage box to a project of its own.

I still have to check if this actually works in practice, but I am hopeful. I based it off their documentation here: https://docs.hetzner.com/storage/object-storage/faq/s3-crede...