Create a custom page on your store with a default template.
Create a collection of the subscription products which you want to display on this page.
Render the collection on the custom page and display all the products along with the variant and quantity selection if required.
Use our Plans API to fetch applicable subscription plans for all the products.
The moment customer clicks on checkout use our initiate checkout api to send the respective products along with their unique selected plan id.
Redirect customers on checkout using the url returned by calling the checkout API.