I believe you might be right, interference is exactly what you want from a quantum computer I think.

And the test they did show that they actually achieved interference. How you'd call that quantum supremacy is a bit of a strech tough if you ask me. Looks to be like saying 'hey, a quantum system can simulate quantum behavior quicker than a classical computer' which is kinda implied

No. Interference is what makes quantum computers work. Decoherence destroys superposition.