qmk_firmware VS qmk_tool

Keychron C1 TKL Board with non-RGB backlighting; foam, tape modded and flashed with SonixQMK Tecware PBT OEM Keycaps (White and Grey) with the Keychron C1's orange ESC key which is ABS Akko Jelly Purple Tactiles with the modifiers (except both Left and Right shift) being Akko Rose Red Linears Didn't bother to lube them, I'm just lazy and don't have a switch tray :D Stock plate-mount stabs lubed with Krytox 205g0 and Dielectric Grease

I think you should give it a while and get used to it and pay attention to https://github.com/SonixQMK/qmk_firmware and in particular this PR https://github.com/SonixQMK/qmk_firmware/pull/318 which will bring QMK/VIA support to the white backlight version of the K2V2. Something you will never get with the RK84.

In theory you could use SonixQMK. But this will require you configure the source code, compile it and then download it to the device. You could then use the Via utility to reassign the keys. This might work, but I have found Sonix QMK to unstable in the long term on some Keychron keyboards. No one is going to tell you how to do this with a simplified complete set of instructions. You may get stuck with a keyboard that doesn't work and if you aren't experienced or don't have the tools there may be no way back.

Well not quite... While the K6 pro supports qmk and via out of the box, there is also support for the normal K6 within this fork of QMK https://github.com/SonixQMK/qmk_firmware

How can I compile and flash the qmk software from here(https://github.com/SonixQMK/qmk_firmware) onto my Keychron K2?

Just as an FYI, if you're ever adventurous, if you have a rev2 or rev3 GMMK Compact, you can load QMK/VIA from the Sonix Branch.

SonixQMK

The SonixQMK fork has support for Keychron K2. I'm not sure if this is for the V2 or not, but it could be worth checking out.

Yup ! It's supported : https://github.com/SonixQMK/qmk_firmware/tree/sn32_master/keyboards/keychron/k6

While there is QMK for the K3 https://github.com/SonixQMK/qmk_firmware/tree/sn32_master/keyboards/keychron/k3 it seems to be for the RGB variant only while your K3A1 seems to be white backlight according to https://www.keychron.com/blogs/production/project-update-for-the-k3-pre-orders-1

It’s a rev4 board which has a different MCU with 8kb ram, 64k flash, and an 8051 arch. https://github.com/gloryhzw/qmk_tool/wiki/GMMK-REV4

You can try flashing SonixQMK on your keyboard, howto. Be aware that you should check your keyboard to see if it's supported or not, as Revision 4 of the GMMK is not supported.

There is QMK support for the GMMK, just unofficially. Also, you can brick your GMMK when going that route. However if you're still feeling up to it, here's a guide on how to https://www.youtube.com/watch?v=aUiKHdI5Vk8 If you follow that and most importantly install the Jumploader, things should be on the safe side. The best precompiled firmware for the GMMK you can find here: https://github.com/gloryhzw/qmk_tool/wiki/VIA-OpenRGB-for-GMMK This implements both VIA and OpenRGB. VIA lets you remap your keybindings and create macros and such, while OpenRGB lets you control and customize the RGB on the keyboard.