Is it possible to only use shopify as frontend with everything come from external backend

[SpringField135]

This is maybe sounds dumb, but the thing is i already have the backend already hosted with all functionality to assert my client needs. Is it possible to just the frontend part of shopify but all the data come from external. It cover auth, product, order, cart, etc

[PaulNewton]

Custom storefronts

https://shopify.dev/custom-storefronts 

Or more simply buy buttons to embed shopify 

https://help.shopify.com/en/manual/online-sales-channels/buy-button 

https://shopify.dev/custom-storefronts/tools/buy-button 

[Sonya_Yuan]

unluckily,  it is not possible.  you either choose shopify or develop your own e-commerce