I'm building a site for a client which needs to have the option to enroll in subscription plan for a product add-on (Product A) on the page of a different product (Product B).
Product A is unlisted by itself — it is simply an add on for a stand-alone product.
I'm unable to find any documentation for this using the Shopify App. I'm quite fluent in Shopify Theme / Liquid / JS — just can't find any examples and the tinkering I've done (editing metafields, passing product info into the ReCharge snippet) hasn't led me anywhere.
I'm aware of the Upsell app for ReCharge but this seems much too robust for a simple use case.