They do have an EU Central region (see [1]) but "it is not possible to have multiple regions under one account" - you need an account in each region (although it seems you can maybe fudge around with groups to emulate multi-region access.)

[1] https://help.backblaze.com/hc/en-us/articles/360034798433-Ca...

B2 used to only have its own slightly different B2 API, but now has compact with the s3 api.

As far as their offering, one should definitely understand that there are limitations and do their research.