Yes, there are two steps. The bluetooth module itself has to have a program running on it that basically just copies between a serial interface to the M2 and the bluetooth. This is programmed by putting a passthrough sketch on the M2 then using that to program the ESP32 bluetooth module. After that is programmed then you put M2RET back on the M2. M2RET understands how to use the BT module if it is installed and working.
Yes, I did post a demo on youtube where I did all of that and showed that it works. It is a little bit difficult to get it all working. Probably the most difficult part is getting the passthrough to work properly to upload to the ESP32. That part can be frustrating to get right. Have you tried to upload to the ESP32? Did you have any success?