I think step one would be to define a scope. "Everything" feels like a non-starter. Photoshop in the terminal? Video editing in the terminal?

I don't think every app needs to be a CLI app, but everything should have a robust API, accessible via terminal commands, that allow all the functions of the GUI to still be possible. AppleScript and Powershell have made some efforts at various times, but I don't think either were fully realized, especially when factoring in 3rd party developers.

What do you mean by everything? And does that everything need to be done in the terminal (or can/should it)? And who is the user base for this sort of thing?

Such as Wordpress installation? Making a new invoice?

That every tool or SaaS should have a TUI/CLI? I saw it today in parallel.ai - in dashboard (website) you press slash and get a list of all commands…

I would like to use keyboard only and everywhere as from mouse I have pre-carpal tunnel…

I agree with you. Im noting more and more how just about everything can be done more easily from within a terminal, bypassing layers of UI.