i dont accept that for a second.The M chips are very power efficient and run cool relative to Intel equivalents, but they're not magic, they still produce heat which needs to be dissipated and consume energy. The Mini's smaller chassis and correspondingly smaller battery would struggle with an M chip.
The chips are tiny. There is more than enough space in the mini chassis to dissipate any excess heat...
... and how exactly do they manage that in the Vision Pro?........ if they can put it in there they can certainly put it in a mini.