One of the main reasons I went with Canon as well was the overall more natural look and feel to it rather than have a digital tone to it.

The Canon 5DmkIV was released in 2016 and is an excellent camera. At least for some Canon cameras that have banding problems, the banding changes from frame to frame and averages out quite well. It talks a bunch of dark frames does the banding average out? If so, you are good to go.

I have not seen data for the R6 but other recent Canon cameras are superb regarding low level patter noise.

The trend that is showing across manufacturers is that cameras with smaller pixels have better low level uniformity, including lower banding noise.

Avoid cameras that filter raw data. Variations in filtered raw data vary from deleting stars to turning star color to green or magenta (there are no green or magenta stars). For a partial list of camera models known to filter raw data see the links in this page: Image Quality and Filtered Raw Data

Camera models from the last 2 or 3 years show significant improvements over earlier models and have better low light uniformity, low dark current, excellent dark current suppression technology and more models with flip-out screens to better dissipate heat. Mirrorless and DSLR models that do high rate 4K video may also have improved heat dissipation.

The R6 is a very recent camera, but the low megapixel count makes me wonder about pattern noise.

Recent Canon cameras with superb performance, both astro, as well as action and everyday use is the 90DF and R5.

My Canon 90D gallery Note that the 90D is so good, the Lagoon nebula image is from stacking out of camera jpegs!

My Canon R5 gallery