It seems you don't understand how the cross-type AF works. They use alternating row pairs of dual pixels in orthogonal orientations. It's not a firmware change, it requires the splitting of the DPAF photosites to differ from row to row on the sensor, meaning a new architecture was required for the entire sensor, since cross-type AF is available across the full FoV.
I wonder why Canon didn't do as you suggest, and make the R1 with a higher MP sensor?
I suspect it's because the company that has led the camera market for over two decades, through a 90% contraction in the market and a transition from DSLR to mirrorless while maintaining dominance of that market the entire time, knows a lot more about making and selling cameras than any of us.
Personally, I thought they were making a mistake in discontinuing the EOS M line. It was the most popular camera line for a while, at one point 17% of all cameras sold in the world were M bodies. Canon killed it off anyway. They kept their near-50% market share, and last year they held over 40% of the mirrorless market share (a very solid lead over Sony at 32% and Nikon at 13%) despite killing off the M line. So much for my opinion about what Canon should or should not do.
The bottom line is that they have an excellent track record of producing cameras their customers will buy. It is very unlikely that the R1 will be an exception to that, the whining and second-guessing occurring on the internet has occurred with most new Canon releases. If any of that was actually relevant or impactful, Canon's sales would have slipped. They haven't.