I don't have an M6 II, but I do have an M3, 5DsR and a new R. In earlier tests, I found that my 24MP M3 was similar in IQ to my 6D mkI at low ISO values, although the 6D had better dynamic range. Neither are close to the IQ of my 5DsR. My 5DsR is sharper in real world images than my EOS R, which is 30MP, like the M6 II, but you would need big enlargements to note the difference. I suggest that the M6 II will provide resolution on good lenses similar to the R at low ISO values, but probably less dynamic range. The IQ would be adequate for all but the most testing images and large enlargements. The 30 MP will test your lenses, the 11-22mm is fine, the 15-45mm is not.
I think the biggest difference is in (1) the size and (2) form factor. I hiked east-west through the Swiss Alps and bought an M3 specially for that trip to save weight. This proved to be a good decision. An M6 II would be better. In terms of form factor, the flip out rear screen is invaluable for macro and I preferred to use my M3 over the 5DsR for outside macro shots.
To conclude, I suggest that the 5DsR will have better resolution and probably better dynamic range, but the difference will be marginal in most situations. However, you are more likely to take an M6 II hiking to capture magical landscapes.