Being built with the Catalyst framework which is only available in Catalina seems like a pretty good reason to only have this available in Catalina.

I stand corrected. I didn't read far enough to know that this was Catalyst.

Likely didn’t have the required apis then for this to run.

Catalyst != Marzipan, not even architecturally.

That they develop new products that show off the capability of their new products? It would seem odd to me if they did not.