stenogotchi VS qmk_firmware

Sounds like you're trying to build a Stenogotchi

If you're familiar with Plover, the Stenogotchi might be something you could look at as well, if the devices you're working with support bluetooth.

Yes. Check out https://github.com/Anodynous/stenogotchi

I'm in the same boat, that's why I started working on the Stenogotchi.

Check out stenogotchi [1] if you haven't already. Plover running on a battery-powered Rasperi Pi Zero.

[1] https://github.com/Anodynous/stenogotchi

Definitely. The raspberry pi zero w is particularly well suited for this due to its small size and built-in bluetooth. You can take a look at my hobby project with this same goal in mind, the Stenogotchi, for inspiration.

I only use keyboards running QMK or ZMK, so:

My Caps Lock key is a Control/Escape key (when tapped it behave like a Escape, when hold it's Control), and my left Control is a one shot layer switch key [1], which means I tap LCtrl once, and then press Caps Lock + 5 to get Ctrl+F5. Doable with single hand and more ergonomic as I have an unusually small hand.

[1] https://github.com/qmk/qmk_firmware/blob/master/docs/one_sho...

I agree that reduced finger movement is a crucial step in achieving typing efficiency. This is nicely solved by mod tap modifiers in QMK/ZMK[1] where key acts as a char when tapped and as a layer while pressed.

[1]: https://github.com/qmk/qmk_firmware/blob/master/docs/mod_tap...

Separate wireless controller, see the glue code at [0]

[0]: https://github.com/qmk/qmk_firmware/compare/master...nuphy-s...

If you have a keyboard that runs QMK firmware[0] with the VIA[1] feature enabled[2], then there is a convenient testing app available from the same place you customize your keys [3].

[0] https://qmk.fm/

I made a layout that I'm happy with. Spanish is my native language, so it has characters like the accents and 'ñ', but it's meant to be used for programming as well. Visual Studio uses a lot of Ctrl and Ctrl + Shift shortcuts, so I left them in the same place as the default Corne layout so I can press them both with my pinkie finger. Perhaps some of the ideas are useful to you.

Also, it would be possible to do this for the RP2040. However, it needs some work to get working. but for example: https://github.com/qmk/qmk_firmware/pull/20999

Ok, it's an ST7735, not too different from the ST7789. You should be able to get running by looking at their files in the QMK repo and going from there. You should also check their resources page.