Google could make a positive impact by introducing new features that help users seamlessly fund their favourite open source apps, right from their Google accounts. GitHub has recently introduced a similar initiative called GitHub Sponsors [1].
> Taking a step back; it is pretty weird to have apps opening links to web pages that take your credit card number.
There is nothing weird about accepting payments outside of Google Play, and it is allowed if the payment does not result in buying a product that is used within the app. Buying a movie ticket, or operating an online store with a third-party payment processor are perfectly fine use cases which are allowed on Google Play.