I am not sure if this is a legit, but we now have some details about T-Mobile's $100 promo referenced in Apple Watch Series 7 orders start Friday, October 8, with availability beginning Friday, October 15 page.
By activating $10/month unlimited data plan for smartwatches through T-Mobile, you should be able to apply 2021APPLEWATCHRETAIL1 promo code at T-Mobile's promotions redemption page. You should get $100 prepaid MasterCard 6-8 weeks later, at which point you can downgrade to $5/month 500MB data plan for smartwatches or even cancel the plan altogether.Customers can buy Apple Watch (GPS + Cellular) directly from apple.com/store or at an Apple Store and get $100 back when they activate it with T-Mobile/Sprint or Verizon.