Or just use an editor built on this concept, like Helix.

Edit: Okay. I got downvoted and I see why. Let me rephrase:

If you are interested in this editing mode, you should check out editors that are built around this concept, like Helix (and certain vim/neovim configs/plugins). Having native integration makes it insanely powerful (and you don't have to get Emacs pinky from all the modifier presses).