If anybody buys a laser and gets an M3 Nano purple board it has some yet undocumented PWM support, keep the software long enough to figure out the PWM control stuff. Most of the rest should be the same.
The GPIO added to the board (upper left-hand side) is likely just shorting SCL pin on the CH341B chip there and using the returned status as input. But, the PWM is likely hacked into the actual control codes so updating the Lhymicro-gl.
I author MeerK40t and to support the PWM, I’d need to know what it uses to control the PWM. Likely they added a quick control code with a value.