I think Stripe handles Apple Pay (edit: also Google Play, per another commenter). I'm sure there are others. I'd think that Stripe, Apple Pay, and PayPal (speaking of "dark patterns") would get you about 90% of the way there.
That may still be too high a bar for non-technical people, though.
If you wrap it into a “hosted blog” service, it could make a lot of money. You won’t get commissions on the payments without being a “platform,” but that’d be your differentiator. It wouldn’t be a VC style billion dollar business but it could make multiple $100k per year revenue. And you could scale price by number of subscribers (like newsletter providers already do) rather than percentage of payments.
That’s the case now. But a product could provide the hosting and setup for the writers. It might not attract the same VC-level returns as the platform play of Substack, but it could be profitable and steal writers from them (especially writers who already have their own form of distribution and discoverability).
That may still be too high a bar for non-technical people, though.