Just remembered to check the firmware update page and sure enough it has the information on the controller. It’s an ESP32. Probably similar or the same one used by the newer Orturs.
Given that Makeblock is using GRBL for this and GRBL is GPLed, you should be able to request source code for the firmware. Whether or not they comply is another matter. It’s likely based on one of the existing ESP32 builds for GRBL but would be nice to start working from where they left off.
It may be complicated because they may have some proprietary components mixed in there. Either way, might be interesting to disassemble the firmware file.