Hello Felix,
thanks for the info on your M5Stack tuning. I opened the case and managed to get to the MPU9250 however, I am quite sure that I would burn something considering the tools I have. I took a photo of the MPU9250 with the 1.5mm Allen key next to it just to give an impression of size.
I have purchased some ADXL355Z and will try a "conventional" solution. BTW, to open the case I followed the instructions given here (https://forum.m5stack.com/topic/257/replace-cracked-screen/6).
Cheers,
SpeedyG