If it’s like the LaserPecker 4 (which I have here) GCode wouldn’t move the mirror. The Mirrors will be moved by their Galvanometer control software and It’ll produce a reasonable representation of what the GCode is asking for.
You may also need to select constant power for the laser control (depending on how the laser is intended to work).
Please connect to the Galvo laser with LightBurn, select and copy the text from the Console window and paste it into a reply here. I’d like to see the first messages between LightBurn and your engraver to see if it’s similar to what I have here. I’d also like to confirm the Firmware version number.
I’ll see if I can find some setup docs from the manufacturer.