Free/Cheap hosted Pro server allowing S3 backend

Are there any cheap or maybe even free hosted Pro servers that allow to configure S3 as the backend?
My rationale: I’m happy to use Backblaze B2 as my storage and pay the storage fees, but I’d prefer someone hosting the seafile server for me and keeping it up to date and running. Pro hosting mostly charges for storage, which I wouldn’t use.

Backblaze does not fully support S3 API and thus doesn’t work afair.

That information is outdated. As of October 2020 Backblaze is fully S3 API compatible. I’d like to link to the backblaze article, but I don’t have permissions yet in this forum. https://help.backblaze.com/hc/en-us/articles/360047425453 and https://www.backblaze.com/b2/docs/s3_compatible_api.html

Searching this forum tells something else: Recovering from S3 storage failure?

But, you’re welcome to try it out.