Hello i Have the
Kobra2Pro Printer direct from AC with a newer Mainbord the Mainboart printing Spe_B_V1.0.5 
with a Firmware Version 3.1.2.3 and have a Rockchip and HC32F460 chip
(i have a older Board with V1.0.0 and this is root und have webserver)
I have already searched a lot and found a lot of information, so the firmware file looks exactly like the one from Kobra3 and is a password protected zip file with setup.tar.gz file in it with I have already been able to create backups using various .swu files. My goal would be to create a working CFW like with Kobra3, but I haven’t quite managed to do that, something is different!
this is the CFW from K3
this is the firmwarefile from Anycubic K2Pro
https://drive.google.com/drive/folders/1nFJAXBey12f40RSBXfZcdZZS--gQ0zXd
the password is always
U2FsdGVkX19deTfqpXHZnB5GeyQ/dtlbHjkUnwgCi+w=
have everyone other infos or can help i not a profi 
UPDATE:
jbatonnet have make a very good cfw for the K3 and we have modificate the Code!
The K2Pro with the Firmware 3.1.2.3 (PCBboard V. 1.0.5) is supportet
Have Fluidd,Mainsail,SSH 
thx
moosbewohner