Fair enough, here are some additional info:
Apple Watch Series 4 (GPS + Cellular)
Version 10.6.1 (21U580)
Model:A1976
I finished the transfer from my old iPhone 13 Mini to the new iPhone 16 Pro, and the Apple Watch was working, but not paired to the new iPhone 16.
Checking the Watch app in my new phone, I can see the Watch there (and I cannot see it anymore in my old phone), but it's saying "Pairing Not Complete", then I clicked in the "Finish Pairing" and it says Unable to Connect to Apple Watch - Make sure your Apple Watch is nearby and on your wrist to finish pairing" then I clicked Ok. The phone is close to the watch and on my wrist.
I tried to reboot both the phone and watch, no luck. From the new phone and can see all info related to the Watch and I can also locate and play sound using "Find My" app in the new phone, it's just not allow me to pair the Watch with the new phone.
I think that's it. If you have any more questions please let me know.
I appreciate any help.
Thanks in advance.