Extension only Apps for non-Plus stores

Ive spent quite some time developing a simple Shopify function extension to automate product discounts based on quantity and a custom metafield then to only realise I cant deploy it to my client as he has 2 x Shopify Advanced plans (not Plus).

It seems very time consuming to try and publish the app publically so this is not really an option.

Do Shopify have any plans upcoming to allow custom-apps (single store) to be applied to non-Plus users in the near future? If so, we intend to wait for it as Shopify Plus is far too expensive for the business.

Are you me? I created almost exactly the same function for the same purpose but I also just found out that it requires a public app for the advanced stores I maintain.
Did you ever find a solution?

Yes I actually built a public app..painful process..