I've done a similar thing at the hardware level using a QMK layer. The main benefit for me is being able to use VIM movement keys in every text input. As I'm using a dual boot setup, it's also pretty handy to have the mapping directly embedded in the keyboard firmware.
Thanks for mentioning QMK [0], it's not something I've heard of before, and it seems like a huge step up from standard keyboard firmware. As far as I can tell only a small number of manufacturers officially support it, but at least one person seems to have made some progress getting a standard cooler master keyboard to run it [1]. [0] https://qmk.fm/ [1] https://github.com/qmk/qmk_firmware/tree/master/keyboards/bp...
I have worked on Teensy 3.6 support for QMK, and plan to work on Teensy 4.x support as well.