Yes, I agree. In fact, GoodNotes abandoned it’s earlier approach to creating a new Mac version (v5) the old way, and adopted the Catalyst approach. There is now a beta available on Catalina of GoodNotes 5 created from the iOS app via the Catalyst framework. No doubt there will be many other apps that do the same.

satis wrote:

I think that next year we'll see the beginning of a potentially mass
migration of the better iPad apps to macOS, using Apple's Catalyst
framework announced this summer at WWDC.