Currently, if I’m not missing something, we can bill customers based on the products we define, but they cannot, apart from hosting reseller products, actively buy products or add subscriptions via the client portal.
It would really be great if customers could just go in and buy additional products or services in a self-service fashion (like they can do for hosting reseller products already). Ideally, we should be able to maintain a description like for the reseller products for other products as well, and also use the product display embeds the same way.
Like this, customers could directly buy maintenance or development packages together with the hosting package, or add them later on if needed.