It would be really interesting to support Image serving in the M291 command to better allow setup procedure to be shown that aren't easily described using text.
Use cases would be things like CNC setups, cleaning procedures, bed prep procedures, warnings to clear certain areas, etc.
I( have a couple of procedures where it would be really helpful to allow operators to check visual references against an image.
This could even be a pi exclusive feature if the Duet 3 MB6HC can't handle serving image files.
See this reference from HAAS on what this could look like. Massive Cheese warning....