What’s interesting is the iPhone Bluetooth experience with Apple products is excellent. I remember my partner used to have an Android wear watch for her Android phone and it was constantly disconnecting and having to be disconnected/reconnected to fix issues. When I got my Apple Watch, I couldn’t believe how smooth the experience was. To the point where if you didn’t know it ran off Bluetooth you would think it is some new protocol. Similar experience with AirPods as well.
I’ve had some issues with AirPods and AirPods Pro, but they are much rarer than other bluetooth devices I’ve used. I use AirPods Pro several times a day and for hours a day so even with a very low failure rate I’d expect things to break occasionally.
re:Watch, it is likely using WiFi at least some of the time. My Watch shows up on my WiFi and conveniently connects using the same network as my phone, so it apparently knows the WiFi credentials from the phone, at least on a personal network. I never explicitly set that up, and getting Watch to stay off WiFi isn’t something I persisted at - mainly because it does help create a more perfect connection experience than is possible with Bluetooth.
I discovered this initially when I was charging my Watch, while well outside of bluetooth range but just barely in range of WiFi.