Do you really need it to support all of these different backends? I bet this would more likely come to exist if the authors knew they could focus on a subset of these.
As a developer if I knew you would need to support a ton of backends i will spend significant time building a abstraction layer which is backends agnostic and a framework to add backends easily. It would then be much easier to add new ones, even if I don't want to support them immediately
Alternatively i would add support for one or two services directly, rewrite many times and come to the above model and add support slowly.
Knowing you would need all of the backends would help immensely in the initial design
It would be acceptable if it only existed for AWS and GCP at first. But ideally yes, it should aim to support a variety of them for freedom of choice and redundancy.
