On November 4 I bought a Apple Watch Series 7 directly from Apple. They kindly told me about Verizon's rebate in a confirming email, specifically:
Within 30 days of receiving your new Apple Watch, activate a new* consumer postpaid data line. You'll then have 30 days after activating your new cellular service on your Apple Watch to complete the rebate submission at vzw.com/myverizon or use the MyVerizon app (go to Notifications to complete the rebate submission). Within eight weeks of submitting your application, you'll receive a $100 Verizon gift card.
I attempt to go the the URL where I'm able to log in. It asks for a "Promo Code." Neither Apple nor Verizon support have been able to tell me that code. I see nothing under Notifications to complete the submission.