Open chromium.
Go to https://usevia.app/
You might see the error:
Vid: 0x3434
Pid: 0x0273
Then navigate to:
chrome://device-log
See which device you are trying to write, in my case is:
HIDEvent[13:31:37] Failed to open '/dev/hidraw2': FILE_ERROR_ACCESS_DENIED
HIDEvent[13:31:37] Access denied opening device read-write, trying read-only.
Then allow write access with:
sudo chmod a+rw /dev/hidraw2
Do your changes in your keychron keyboard.
When you finish, remove the permissions with:
sudo chmod 600 /dev/hidraw2