Can I use a XT M8000 power meter on a XT M8100 crankset?

Great question! Unfortunately not. Shimano changed the spline depth on the Mx100 series. Therefore you would need a XT M8100 specific power meter.

We have a separate article that explains all of your XT M8100 power meter options: What power meter will fit my Shimano XT MTB crankset?