Does anyone know if the slide of a P220 Compact will fit and function on a P220 full size frame?

Yes, but you may or may not have accuracy problems, as the locking blocks are different. Full size P220 locking blocks are marked with 5 dots. Previously on this forum some reported no accuracy differences. I for one tried it and groups went from 1.5" to 4" at 10 yards. Corrected by changing to correct locking block.

Thank you

220 compact slide on a 220 full size is exactly what the 220 carry is.