You may use any JS client and do not need to run node. I personally rewrote an entire store then deployed to JAMSTACK using the Storefront API as the client was not satisfied with Shopify’s non-commerce features (pages, blogs)
Apollo is great however the stack is pretty hefty. So we implemented all queries and mutations through axios (though you could use fetch for all that matters) as long as everything is formatted properly the how doest really matter.
Regarding the payment method, unless you can integrate that payment as a gateway in shopify you would have to create a separate checkout and then “create” the order afterwards marked as PAID in shopify, it would be a bit convoluted to be fair…