There is hardware which purportedly does a quantum computation, but it's completely useless even as a proof of concept, unless you have a burning need to randomly sample from the distribution it happens to generate.
An interesting idea is simulating quantum math on real hardware. It's an open question if quantum computing is equivalent to contemporary computing. It seems likely that it is.
We might have different definitions of "proof of concept", but I think that's exactly what it was (if you're referring to Google's experiment).
This FAQ explains this quite nicely:
https://scottaaronson.blog/?p=4317