Well... If this watch runs Wear OS, then the problem could lie in software development. Oxygen OS breaks connectivity with Wear OS. After 5 months of owning an OnePlus 8 Pro I finally made my phone connect to my Wear OS watch, but it took an update to Oxygen (Android) 11 and a complete reset of both the phone and the watch to make the two work together. Now everything works but this is not normal "out of the box" functionality for the average customer. Maybe OnePlus is trying to make the process "somehow smoother than that".
As with ANYTHING released by Oppo's OnePlus, even when it is released, best to wait about 3-4 months until they announce the "T" version to grab one. BUGS
Never will be...that's explain it a lot.