There has not been supersonic civil aviation but "supersonic" is not the interesting point here. "Supersonic" is easy and solved often in aviation. The question is what else can they do to make it work. And there is no aircraft yet, just a scale model. Progress sure but not because "supersonic". The new engine would be more interesting.

And how is this a civilian aircraft? It is a cool one-off single seater with three military engines (oops, civilian engines derived from military and used in business jets - still not cheap for a one-seater). Two-seater for some definition of "technically". But perhaps they can sell a few of these to private pilots and then it would be a supersonic civilian aircraft. One pilot and one passenger if we insist on making it a business jet.