If you wanted to write a shell that has mouse support you could certainly do so, and this would be based on sending escape codes to the terminal to tell it to return mouse events as input rather than let the terminal consume them itself. The shell could then itself support the clipboard if it wanted to, as well as support mouse editing.
I just googled it, and apparently "fish shell" does exactly this, but your hypothetical user is more likely to stumble upon a bash shell which is letting the terminal emulator consume the mouse events and support copy and paste.
https://github.com/lrstanley/bubblezone
There are a lot of components that resemble things you find in web component libraries
It runs poorly, loses keystrokes, and easily gets bogged down with too much terminal input.
I don't want candy coated monospace ASCII graphics. I want something fast and functional. The graphics are _entirely_ secondary. You've missed the point of what a TUI is.