An "AppleTV" is a little streaming media terminal. It plays content using one or more apps that are installed from the AppleTV app store. The apps are things like "AppleTV", "Hulu", "Netflix", "Amazon Prime", "Smithsonian", etc. The "home screen" for the device has a background that shows whatever content is "up next" in the app that is currently highlighted. I.e., if I was using Netflix when I last used the device, then the next time I turn it on it has a background that shows what content is "up next" on Netflix. It does not constantly push you towards Apple's content.
If you enter the AppleTV app, it has a variety of options. The "home" screen shows you all of the "up next" content for all of the apps that you have allowed to share their "up next" information with the AppleTV app. You could theoretically use this as a launchpad for each of those shows in their native app, but I've found that it didn't work well enough for me to use in this way. The "AppleTV+" page shows you the content available with an AppleTV+ subscription
Apple's nomenclature can be a bit confusing, because there is "AppleTV the device", "AppleTV the app" and "AppleTV+ the service".
I don't feel pushed to go to the AppleTV app. I primarily use the apps for Hulu, Netflix, Amazon Prime, Peacock (NBC), and YouTube.
I tried out the AppleTV+ service when they gave me a free subscription, but found it somewhat confusing to determine what would come with the subscription versus what would cost extra. Some of the content seemed like it might be good, but it wasn't compelling enough for me to dump something else (how many paid streaming media subscriptions does one need?).
An AppleID only needs a payment method on file if you plan to buy things with it (like renting a movie through the AppleTV app). I have a few bucks on mine from an Apple gift card, but no credit card on file.