one issue with using variants to represent apples vs cases of apples, is that inventory won’t be tracked accurately. it can still be useful to for producing invoices/etc, but you need some manual steps to link the case to the sub-product (apple) - but i see that @MyriamBoure has detailed that in the issue she linked ( Quantities “on hand” adaptating when variants are a sub-product of the main product )
there is actually a spree plugin that allows a product to be made up of other products: https://github.com/spree-contrib/spree-product-assembly - but i’m not sure how it would work here or if it is suitable. we did have some issues with it not tracking inventory as you would expect, but it was very useful for us when creating ‘packs’ of mixed products. to be clear how this could help in the “sub-product” issue, you could have an assembly (case of apples) that requires X parts (apples, or bags of apples, whatever is in the case) where X is the case size.
but i’m not sure that plugin is entirely a good fit. the use case here is quiet different: we care about determining upstream demand (cases) from downstream demand (member orders). the plugin was designed to ensure downstream orders can be filled based on upstream inventory.
i often find that being clever with how you model something gets you into trouble later. it does not stop me wanting to try that though - sometimes it works, but sometimes it won’t be perfect… and it can end up being more complicated in the end.