You can prefill the customer info by using permalinks.Here is the documentation for the same https://help.shopify.com/en/themes/customization/cart/use-permalinks-to-preload-cart . But user can still be able to change that when they switch back to customer info page and to restrict that you'll have to write some custom javsscript on checkout page which is only available for plus plans as of now.
Any reason why this feature wouldn't work anymore? We re-enabled a feature making use of checkout permalinks after disabling it when the pandemy hits and it seems like it's not working anymore. We used to be able to set the shipping address with the URL parameters but now it seems like the customer default address won't be overridden by the parameters in the URL.