nanoCH32V203 VS qmk_firmware

If you are willing to try r/RISCV ones, then nanoCH32V203 (with two Full-Speed interfaces) and nanoCH32V305 (with one Full-Speed and one High-Speed interface) might be enough.

There are dual USB r/RISCV boards with GPIO pins exposed, like nanoCH32V203 and nanoCH32V305.

Another alternative is to use dual USB MCU board like nanoCH32V203 as USB CDC relay.

RISC-V boards cost $3-$6 depending if you want high speed USB or full speed one.

Their earlier boards like nanoCH32V203 and nanoCH32V305 were more user friendly, one could flash those via USB without WCH-Link.

Muse Lab has MCU boards like nanoCH32V203 and nanoCH32V305.

The same form factor as nanoCH32V203, but with more RAM and storage, also one of USB interfaces is high speed and SDIO is native this time. Comparable to CH32V307 boards, but lacks ethernet port.

Speaking of hardware there is very nice $3 RISC-V board that would fit well USB to USB converter use case. No keyboard firmware is ported to it yet.

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.