There really isn't going to be, besides giving them your card directly (or paying crypto🤢). PayPal is less about the software and more about the service, which isn't something FOSS can really replace. An alternative would have to have a company behind it that works with major financial institutes and whatnot.

How is Apple Pay just as bad? I haven’t heard anything that they do like this. There is no advertising in the Apple ecosystem. In fact, several places (like Walmart) don’t want to adopt the tap to pay because for some cards, it blocks tracking from them by using a pseudo randomized credit card number every time. It makes using the rewards for places a pain, but it works at maintaining harder tracking for whoever you’re paying.