> Many of these either vanished or transitioned to something else (I think both Komodo and Celtx did).

I know Celtx decided to drop the concept of desktop app altogether and went full web-based-only SaaS.

The desktop Celtx app was a good screenwriting program that was easily affordable for hobbyists and the pivot to a paid subscription service with less focus on just screenwriting and more focus on other preproduction activities left a small hole for a short while. (These days the Fountain ecosystem seems the best suggestion for the hobbyest screenwriter.)