While its not a Canon solution, I have a Pluto trigger that I use for lightning and it has a wireless shutter option that you can trigger from your phone. Tested and works fine with my R5.
I have a BR-E1A and an R6. I could get them to pair, but they never would connect. While troubleshooting, I paired the remote with another R6 and it worked. I then repaired with my original R6 and it worked again. Something about connecting it with a different body seemed to "wake up" the remote and it now works OK. Not the same issue you have, but it may be worth trying repairing to a different body and then going back to your R5 and trying again.