You don’t need an Apple TV set top box to watch Apple TV+, nor do you have to pay for a subscription, see: How to watch Apple TV+ for free. You can subscribe to Apple TV+ on Apple’s website ...
Apple TV+ subscription can be availed within the Apple TV app on iPhone, iPad, Apple TV, iPod touch, and Mac with a seven-day free trial. Also, select Android smart TVs to support this app.
Amazon announced that, later this month, Apple TV+ will be available as an add-on to existing Prime subscriptions. For $9.99 a month, you can get Apple shows like The Morning Show, Pachinko, Shrinking ...