To update, what worked for me was to get an old phone (in my case, a phone with iOS 14.7 but could be many older iOS versions) and use that to activate the watch. Then use that phone to complete all updates. I then unpaired the watch with that phone and paired it with my new phone. It worked perfect. The updating process on the old phone took a very long time (a few hours) since the phone was so old, so be prepared.