There is always the risk of breaking something when making software/firmware changes. The “trick” is to be organized. Without version control, the easiest thing is to keep labeled and annotated versions of your firmware as you make changes, so you can always roll back to a place that works. In your case, you need to keep copies of configuration_Adv.h and pins_MINIRAMBO.h. Or you just download a new copy from the V1 github page to roll back to your starting version. Note that in order to get the laser support working, you have to make the changes that I highlight in the file comparison that is in the other topic as well as assign the laser to the correct pin.
I dont want to accidentally mess up anything trying to make the laser work
In my mind, the important questions is can I make changes that damage the hardware (laser in this case). I’m not an expert, but I cannot see how any of these firmware changes can damage the laser. In the few cases I’ve read about where a laser is damaged, it is someone using a 12V fan pin to drive a 5V PWM input to the laser. In your case, since the laser is 12V compliant and you are using a 12V pin, I cannot see how you could damage anything.
So try it. If you cannot get it working, roll back to the version of the firmware you are using now.
P.S. If these changes do work to enable G0/G1 commands with the laser, I’d appreciate knowing since this is all theory to me at this point.