HTML as a TUI
Using a TUI browser, such as eww, lynx or chawan, you can get a surprisingly nice tui "for free" if you create a website with semantic HTML.
One such example is Sourcehut Builds, which works entirely from a TUI browser.
This website is built to be easy to navigate from a TUI, so I can lookup my posts and references directly from the website itself without needing to open a full-blown browser.
I also have a CLI command to quickly create new git repos on my server, which is done by aliasing w3m to a page with a form.