Setting up the Apple Watch Ultra 2

OK. I made a mistake. I got an Apple Ultra 2 watch from T-Mobile with cell service. I didn't know it required an iPhone to setup. I don't think I can back out of the contract. My question is, if I buy a used iphone 13 from eBay, use it to setup the watch, without the iphone being under a contract or activated by a carrier, will it work? Will I be able to setup the watch. With cell service, the watch will have access to the internet. If the watch needs updates from the phone, I can use the iphone 13 to connect via wifi to the internet, and get updates.

So, will my screwball idea work? Or will the iphone 13 not access the internet or setup the watch because the iphone needs a carrier to let me use it. Some cellphones only partially work without a carrier.

I have a Macbook Pro, not the latest IOS, but I bought it so I can relearn what I forgot about IOS and Apple. My other option is to get an emulator, and see if I can fool the watch. I just don't think there are emulators for IOS. I did something similar with an emulator for a cheap webcam.

The webcam was designed to work with android. I didn't realize how cheat it really was. No real proprietary software for it. Limited only to the 2.4 Ghz band. I just wanted to see if I could get it to work. So I got an emulator to connect to the webcam on a Windows 7 PC. The emulator was able to connect on the 2.4 Ghz band, rather than the 5 GHz. And I got the webcam to transmit images to the PC.