@FrodeBNilsen MIR is documented in the github link I posted in my reply: https://github.com/Apsu/Mir
See this video for a run on my prototype (would need proper re-engineering to work, time I dont seem to find): https://streamable.com/vczvhu
My config from back then is at https://github.com/oliof/printerconfigs/tree/main/minimir
Regarding larger PEI sheets: I got nothing on this, I am more into small printers.