Did you ever find a definitive answer to this? We have a very similar scenario and can't seem to get good guidance from Apple before we invest in implementation.

Mar 210, 2021. Trying for DAYS to get this to work. I've reinstalled the OS on every device: my iMac, my iPhone 12 Max, the Apple Watch... everything. Oh how I love spending weeks developing an app only to be blocked from progress. UGH! Is anyone at Apple actually monitoring this thread?