I wouldn't hold your breath for this. I think Hetzner wants to stick to compute offerings, they don't have the manpower to run managed services like object storage or databases.
Wasabi is a great, inexpensive object store for anyone who's looking for that. I've had a really good experience with them (we have a little over 80TB of data there), and have found their support to be top-notch especially when you consider the price.
It wouldn’t even needed to be integrated to their API and billing.