The key micro RP offered by abitkeys is another RP2040-based controller with some extras.
KBD.news Published March 10, 2022
New week, new RP2040 based controller.
This Pro Micro-sized development board, similar to the Adafruit KB2040, is another option for building keyboards with the RP2040 chip, CircuitPython and KMK. Let me not repeat myself.
USB-C, 4MB flash, Pro Micro compatible pinout, but this one comes with some interesting differences.
E.g. "side-push" Reset/Boot switches pointing to a direction where, depending on your layout, you can use them even when the board is soldered reversed.
In addition, extra Reset/Boot switches can be soldered on the back side.
No LEDs and the PCB is a completely black silkless one – blending into your design.
About 2 mm overall thickness.
Regardless of its availability, the board is fairly expensive, about $17, compared to a $4-5 Pico or $9 Keeboar.