Implementing Apple Pay and Google Pay to react-native mobile App(storefront API)

[KfDev]

Hi everyone!
i'm currently trying to implement google pay and apple pay to mobileApp that are using React Native, i have some questions about the API. I've tried searching around the docs and the forum and this is what i got.
- We need to use this API checkoutCompleteWithTokenizedPaymentV3 (shopify.dev) if we use stripe and this is the example Create a checkout with the Storefront API (shopify.dev) of how to use it.

- The recommended way are using Mobile buy SDK for ios/android but that's going to take some times to implement it to react native.

- if im going to use stripe to pay and then use the checkoutCompleteWithTokenizedPaymentV3 (shopify.dev) api to finish the payment. What will happen with the shipping fee and courier? and if i try to calculate the shipping fee myself, how will i track the finish checkout?

Thank you in advance!