I'm worried those EF-M lens might have flange distance that's too short, turning it into RF might end up a 24mm/f2. EF-M15-45 turned into RF-S18-45.
the difference in flange distance shouldn't make a huge difference there.
the lens can always sit a bit further back into the camera body another 2mm.
That being all said, I do wonder why Canon simply didn't move EF-M to RF-S .. especially the 22mm and the 32mm, not to mention the 11-22mm.
That least would have gotten me to consider an RF-S camera body - which with the way it is, it's in the not-a-chance-in-hell category.