Custom storefont to use inbuild shopify checkout

[Mitaanshu]

Hi I have a custom storefront that is hosted on AWS, I'm using the inbuilt checkout option given in shopify but its adding .myshopify.com to the url which i'm not able to surpass. If i move my domain to shopify then it just takes the default template not the custom storefront that is developed in next.js and hosted on AWS. Please help, I want both the base URL to be same.