OS for EdgeBox-RPi4

Hi there,
I haven’t found information regarding the OS running in EdgeBox-RPi4. I believe it’s a common linux, but I’d like to know if I could flash my own custom balenaOS.
Is there documentation regarding the EdgeBox options for this?
Thanks!

I have the same problem.
How can I flash my own image to EdgeBox RPi 200? There is no documentation about that.
On other boards with RPi Compute Module need to insert a jumper to flash image but on EdgeBox there is no place for jumpers.