ibis: If you want to get an impression of all the supported backends, just have a look at the installation docs here. It's truely impressive.
However, the reason it is impressve is also because it is hard. There really is a lot of ground to cover and that also means that it can only support a general API. This means that some features that are specific to a backend might not be supported. That comes with the territory.
Still, if you're running relatively generic dataframe operations that you want to run on many different backends ... Ibis is a project to check out.