I think the most important piece here is standardizing a schema format for command line programs.
Once you have that (and it’s actually adopted) there are many possibilities. TUI/GUI is just one of them. Think autocomplete, type checking, discoverability...
I believe something of this nature was proposed in the Oilshell under the name Shellac[0]. A shell-agnostic autocompletion format so that the world could finally move on from writing bespoke completion protocols for every new shell language.
I'm dreaming of a universal standard based on JSON Schema. Dynamicity is a challenge of course. I guess one needs to strike a balance between static data, say for each subcommand, and a full blown configuration language, say nix.
I hate to be the LLM guy but they're really good at processing semi-structured data to structured data. You could go that route and have a universal autocomplete for the CLI. Kinda like Co-Pilot for Bash, or you could use it to do what the parent's doing and have a universal TUI program for building commands.
Once you have that (and it’s actually adopted) there are many possibilities. TUI/GUI is just one of them. Think autocomplete, type checking, discoverability...