SolvedBozzard For what it's worth, RCS is working on my 9 pro on the Rogers network (Fido). After initially working, it stopped functioning last fall around the time of the changes mentioned above. It took a while, but eventually starting working again. That was after a GOS update or two, a few rounds of toggling RCS on/off and rebooting on my phone, de-registering my number with RCS etc, and ultimately toggling the SIM on/off (which is what I think finally re-calibrated whatever it was that was "stuck").
It's still finicky sometimes and messages to both other Android RCS and iMessage user occasionally get sent as or received as SMS, but that has been the case since I started with a Pixel 8, and may not have anything to do with GOS in particular.