Earlier quoted context omitted.
The downside to ZMK is no copyleft protection. So when you buy a keyboard that advertises "ZMK", you're getting a binary blob you can't customize or audit. OTOH, QMK has successfully forced-open proprietary keyboards that were sold with QMK forks and then repeatedly, emmphatically refused to release the source. This includes the awesome non-Bluetooth 1000hz-rate Nordic Semiconductor wireless feature of the NuPhy Air…
Does that NuPhy QMK codebase include the wireless code, or are they doing the old trick of running QMK on one microcontroller and the wireless stack on a separate microcontroller? QMK has very limited wireless support so AFAIK wireless QMK boards usually use the dual MCU arrangement, and the wireless MCU firmware is probably still closed even if they release their QMK source.
I think you're confusing this with WiFi. The Nordic Semiconductor chips don't require a firmware upload; the protocol they run is vastly simpler than wifi -- it's like UART-over-2.4ghz-GFSK-radio plus some error correction.
https://www.sparkfun.com/datasheets/Components/nRF24L01_prel...
The block diagram doesn't show any kind of CPU in there.