I'm using RocM OpenCL right now, which I believe is the approved option, or will be. Personally I've not had any issues with it - I can certainly use Blender with it, although the performance right now is so-so (I only have a cheap APU though, so hardly surprising).

I don't believe I have any blobs, other than the firmware one, which is true regardless - can you tell me what blobs you mean?