Helios Controller

Works as expected, recommended. Be sure to compile as .uf2 file

For all those QMK noobs like me: to use a keyboard config targetting a different mc:
qmk compile -e CONVERT_TO=helios

This automatically outputs UF2 and renames the pins of the config to match this mc.

This was my first time working with controllers. I used these for my lily58 keyboard build. I flashed both controllers before soldering, and plug in to see they are dectected by my computer. I bought the castellated versions, they worked first time and no issues.

If you use the QMK firmware to flash the controller, you need to convert the file to 'helios' output, which gives you a .uf2 file to drag-drop onto the controller to flash it.
(docs.qmk.fm/#/feature_converters)

Also if you enable VIA in the firmware config you flash, you can use the VIA configurator to update your key maps from the website!
(www.caniusevia.com).

Works like a charm. Though note that this is an RP2040 based microcontroller, so although the pinout is compatible with the ProMicro, make sure qmk compile targets UF2 instead of the usual hex files for ProMicro boards. Also note that the additional first row pins on the Helios Controller. I placed mine a row off but luckily was able to still use it even after shorting VCC and Reset as opposed to Reset and GND.

Pretty powerful. Although I'm not expert on programming controllers, it was easy enough. Be aware that it expects uf2 files.