Apple:

Apple today announced plans to introduce Tap to Pay on iPhone. The new capability will empower millions of merchants across the US, from small businesses to large retailers, to use their iPhone to seamlessly and securely accept Apple Pay, contactless credit and debit cards, and other digital wallets through a simple tap to their iPhone — no additional hardware or payment terminal needed. Tap to Pay on iPhone will be available for payment platforms and app developers to integrate into their iOS apps and offer as a payment option to their business customers. Stripe will be the first payment platform to offer Tap to Pay on iPhone to their business customers, including the Shopify Point of Sale app this spring. Additional payment platforms and apps will follow later this year.

And:

Once Tap to Pay on iPhone becomes available, merchants will be able to unlock contactless payment acceptance through a supporting iOS app on an iPhone XS or later device

And:

Tap to Pay on iPhone will be available to participating payment platforms and their app developer partners to leverage in their software developer kits (SDKs) in an upcoming iOS software beta.

Coming later this year to a future release of iOS and a partner-enabled iOS app.