The whole "program is a model" part makes me think of Smalltalk's image-based system. I never really got used to programming this way myself, but I do think an image-based environment might check some of the author's boxes. With the right tooling, a Lisp might even be a decent choice.
For those wishing to experiment what a current image-based development environment feels like, I recommend Pharo. Probably is the most advanced open-source development environment in the tradition of Smalltalk, available today.
Main site: https://pharo.org/
MOOC: https://mooc.pharo.org/
I tried to go through the Pharo mooc and learn a bit, but dealing with bugs and jank in an complex and unfamiliar UI made me drop the idea pretty quickly. The object orientation aspect of it was interesting, but I just can't get behind a language which is tied so deeply to the use of a poorly maintained UI. At a first glance I'm liking the approach offered by Unison, where you work with an image but everything you need can be done from the terminal, which I think is much easier to maintain and make portably. Creating a nice UI for it can be treated as a separate problem.
