Pairing Verizon watch with at&T cell iphone
Can I set up a verizon cellular apple watch with an AT&T cell phone that doesnt have a SIM card and will only be used with wifi?
You can not get cellular service on the watch at all, from any carrier, unless it's linked to an iPhone with cellular service, and in that case it shares the cellular account with the iPhone.
The only exception is a cellular watch that has been set up as a stand-alone device using family sharing setup, in which case the watch is not, and can not be paired with a phone.