@nickolas you can flash OptiBoot onto your Mana SE Nano with another Arduino using the process shown here https://youtu.be/oce7D72Mdwo . . . this doesnt need the ICSP pins to be available on the Nano, but uses standard pins.
Once you have done this (and gained the extra 1.5k of memory) you can flash GRBL 1.1f, with coreXY capability (activated using config.h), with no problem and have the full capability of the latest GRBL version (i.e. Laser Mode and PWM output for controlling your laser or Pen Servo) . . . there is also a version adapted specifically for Pen Plotting/Servo output available here https://github.com/bdring/Grbl_Pen_Servo