When you look at the thousands of command line utilities available for Linux/Unix etc, it's hard to think of anything that hasn't been already done or easily accomplished by scripting existing utilities. Furthermore, people who prefer CLI (TUI is a less common term) tend to be more technical and far fewer in number than potential GUI users.

In general, concerning TUI tools. I bet, that there're people who will pay for such tool provided they give you enough value for this. The problem is creating this value. If you want to charge for them, you could use license key mechanism familiar to us by desktop tools.

I thought a bit about more examples of command line tools which charge users in some ways:

- docker. There's a paid subscription based in the cloud - terraform has a terraform cloud (and their other tools have commercial offerings) - pulumi works in a similar way

Bitkeeper (http://www.bitkeeper.org/) was a successful commercial command line tool which was successful until was created git and became popular.

Your vision is too wide, so wide, need amazon/google size to work with it. Try to focus on 2-3-5 very narrow use cases, and you will see opportunities.