Helix, just as Kakoune before it, supports multiple cursor selections, even off-screen. 👍 Mouse selections are also not a problem. NeoVim also has support for mouse selection.

Feel free to try it out! Setting up LSPs requires some setup work, but if you just want to try out the editing paradigm, you can just try to edit a plain text file to get a feel for it.

If you have htop installed, run it in a terminal and click, for instance, the column headers.

it was inherent to the terminal that you can’t position the cursor and select text using the mouse, and also inherent that there are not right-click menus

There may be terminals for which that is a limitation, but with neovim in konsole, I can (left) click to move the cursor or select text and right-click to get a contextual menu.

Separately, the TUI libary we use for RESTMan is Brick and does support mouse events. IIRC we only support mouse-wheel scrolling, but there's a lot more that is possible.

So, I think it might worth your time to try some TUI alternatives to your GUI environment.

Your larger point that TUI can't fully replace GUI stands, at least IMO. Even for plain text formats (e.g. dotty) that I want to edit with a fixed-width font, an image (pre)view can be essential to some tasks. I don't usually find that's true for coding tasks, but design docs often benefit from charts.

You don't need a GUI to use a mouse, we could even use a mouse in command line MS-DOS