Note that there's a distinction between Google Pay and Google Play's billing system. Within an app:
- Google Pay is generally used for physical goods or for services that are used in the physical world, while
- the Google Play billing system is used for digital goods and services for apps downloaded from the Google Play Store.
If you are comparing yourself to the likes of Netflix, Disney Plus, and Amazon Prime, it sounds like you are enquiring about Google Play's billing system.
From the Payments Policy:
Play-distributed apps must use Google Play's billing system as the method of payment if they require or accept payment for access to features or services, including any app functionality, digital content or goods.
a. Examples of app features or services requiring use of Google Play's billing system include, but are not limited to, in-app purchases of:
- Items (such as virtual currencies, extra lives, additional playtime, add-on items, characters and avatars);
- subscription services (such as fitness, game, dating, education, music, video, and other content subscription services);
- app functionality or content (such as an ad-free version of an app or new features not available in the free version); and
- cloud software and services (such as data storage services, business productivity software, and financial management software).
As for your question:
How do Netflix, Disney Plus or Amazon Prime do?
I believe they accept payments from outside of the app. That is, via their websites.
Note that if you do go down this route, Google Pay can be used free of charge on your website.