After reading this documentation page I thought that extension-only apps can be published and sold on the app store:
Extension-only apps have a Shopify-populated app URL, which you can optionally change, to build embedded app pages or list your app on the Shopify App Store.
But if I try to create a listing for my app on the dashboard it seems to require the full node backend, hosting, etc. Could someone point me to the resource that explains how to release extension-only app to the app store without setting up hosting? Or at least explain the principle behind it. Or is hosting a backend always required if app is submitted to the app store? Any help will be greatly appreciated.