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.

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.