I believe all you need is an iCloud account. If you do get an Apple TV here’s the best way to subscribe to video services. Subscribe to the video service using the Apple TV app (confusing to have an app with the same name as the device). Then install the corresponding app and watch the programs using that service’s app. This will allow you to cancel services easily and you won’t have to create an account for each video service. The Apple TV app itself is garbage and I only watch Apple TV+ content on it.