The best keyboard productivity I gained was remapping the CAPS key to do nothing in macOS. I’ve been considering remapping it to the `backtick key since I use that so much in Slack discussions and when writing documentation
Well, on most keyboards there aren't actual keys, but instead shift-F1 through shift-F12 produce F13-F24.
did you know that c-a c-e c-n c-p c-d work everywhere in macOS like they do in emacs?