Ask HN: What's the best way to incorporate payments in a mobile app?

I've considered various options out there, but wanted to get an opinion from the HN community.

Use Cases:

- Ideally, I'd should be able to get an escrow payment from an user and be able to return it in some cases, without a fee.

- We don't want to store payment info, or at least store the minimum information possible.

- Payments should clear as soon as possible without unnecessary delays.

- Minimum fees possible.

Suggestions? thanks!