Checkout modification for a non-shopify-plus store. Is that even possible?

[larrougos]

Hi,

due to delivery constraints, I need to get the zip code of a customer before he can add items to a cart. I think this can be done with theme modification and maybe a custom app.

I would need an additional modification in the checkout. This zip code needs to be set as delivery address. It should not be possible to change this during checkout. My question is if there is an option to achieve this with a non-shopify-plus plan. And if so, which options do I have?

Thanks for hints in advance!

[larrougos]

After a day of research, my best idea is to build a public app and using Shopify Functions API to validate cart and checkout and a theme extension with a buy-button block, that checks the cart for an existing attribute (zip) and if not aquire that from the customer.

If anyone got a better idea I'd be happy to read 😉