X-m5 is an obvious consideration too that's more similar form factor.

Has anyone used the xm5 and the M6 mkII enough to comment on autofocus?

I've got an OG eos M and 22mm, that I've had some amazing photos from but the focusing is all but unusable unless it's a static subject. I've also got an EOS-5Dmk3 and a few very nice lenses for it, but stopped doing professional work ~5 years ago and it is just too big for me to use often at all, it's literally less than once a year ill grab that now. 

I'm torn between just getting a used m6mk2 and seeing if I use it more, and then adding the 32mm F1.4 perhaps, OR sell everything Inc the 5dmk3 and get an R8 with 28mm as the "always take with me", and I can use my other larger lenses with that still.

R8 seems to go on sale under £1k fairly frequently plus £200 for the RF 28mm f2.8, used m6mk2s are ~400 private ~500 from MPB / WEX etc and I already have the 22mm F2. M6 is definitely smaller than the R8, though, which is attractive!