So apparently I’m not sure if this a over sight but if you use the Best Buy app, you can buy the free 3 months of Apple TV (free obviously) and it seems you can do this every time the trial ends.

https://www.reddit.com/r/cordcutters/comments/vuchzh/free_3month_apple_tv_subscription_through_best_buy/?utm_source=share&utm_medium=ios_app&utm_name=iossmf

No additional purchase necessary. I was able to redeem, even though I previously had a subscription a couple times.

Edit: In case it’s relevant, I’m in the U.S. Not sure off the top of my head if Best Buy is a thing, outside the U.S.

Edit 2: Before redeeming, my subscription was not currently active. My current assumption is this will only work with brand new or inactive subscriptions, but someone with an active subscription would need to test for confirmation. Also, the redemption link was sent in a separate email, and I’m not sure if it has any kind of expiration. If you have an active subscription, you could potentially order the free trial, generate the redemption link e-mail, and then set your active subscription to cancel and then attempt to redeem after it becomes inactive.