Does your mac support an external GPU? A mid to high end nvidia card may or may not outperform the M3 GPU at a lower or similar price. You can also stick it in a PC or resell it separately.
My 64gb m2 mbp is faster running inference than my dual 3090 desktop rig, and at 64g of unified memory it can hold slightly bigger models than the 48gb of vram of the desktop. The performance of the m2/m3 with a big unified memory is very impressive. Not much difference between m2/m3 though, if all other things are the same.