Apple Watch series 3 not updating to 8.7

Morning,

I've researched the web to find answers as to why my son's Series 3 watch will not update to the latest software from apple. same conclusions, restart or reset the Apple Watch. Some websites go into deleting the downloaded update from the phone, but with the latest OS that isn't an option. We reached out to the local support staff at the Apple Store about 2 months ago. They were able to reset the watch to the point where we could install an update. The new problem at hand is getting the update downloaded and installed on the physical device (watch). My son has the iPhone 12, I have the iPhone 13 Max Pro, neither one (with the latest OS) can get the update installed on the watch. It always hangs on downloading then preparing. What I don't understand is why Apple would put out an update for a watch they deemed vintage??? At least for iPhones, you were able to update the OS over at least 5 versions of the device (iPhone 6 and up) And to top it off make it incredibly difficult for customers to install. There are multiple websites that go into detail about the problem with potential fixes, neither one is working. Figured we'd get at least another year out of the watch with the update. Right now it's a small paperweight in my son's room.

Has anyone had any luck with installing the latest update onto a series 3 watch?