Replacing Checkout REST API by Admin GraphQL API

[justadev2024]

Hi,

I have a Shopify app that builds a custom sales channel. This app uses these API calls to create checkout -> create payment session -> complete checkout.

1. Create Checkout:  POST https://${this.shop}/admin/api/2023-10/checkouts.json
2. Create payment session: POST https://elb.deposit.shopifycs.com/sessions

3. Complete Checkout with the payment session: POST 

https://${this.shop}/admin/api/2023-10/checkouts/${checkoutToken}/payments.json

I know the Checkout API will be deprecated soon, and I must switch to the Admin GraphQL.

Could you please give me a link to the new APIs that I should switch to for step 1, step 2, and step 3?

Thank you.