I've read your comment a couple times and don't quite understand it. What makes you think the Sigma 35/1.4 Art doesn't work on an RF system? Mine worked flawlessly attached to my EOS RP using the EF adapter just today -- on a paid job, no less.
Sorry if I wasn't clear, but I'm suggesting that Canon has an absolutely wonderful ef 35mm f/1.4L II that works even better on the R system than it did on the EF system, and that Sigma has a good 35mm Art also. (I can't tell if those who claim to have an adapter but disdain using it are being facetious. I'm losing my sarcasm detector, I guess.)
I stated that the Sigmas I've kept, the fisheye and the massive macro 180mm f/2.8, work beautifully on the R5, and then ask if the 35mm Art does too. If it doesn't work, why?
Thank you for reporting that yours, as I would expect, works!
And I did have a good laugh when one poster, who, again, might have been sarcastic, demanded that the new 35mm be 1.2...Or else! As if that 1/3 stop at 35mm would have enough real-world significance to theatrically ditch and switch an entire system?