IMO couple of must have features to make it inline with current ecommerce solutions (most are overkill but some are asked for by every client):
Manager/Back end
Product options - S,M,L or other definable variants which also can affect price. Almost like TV’s - highly configurable.
Product reviews - allow a user to rate and comment with modding in the manager.
Product suggestions/Cross sell - allow admin to build ’packages of products’ that can be suggested to the end user during full product page views.
Stock control
Order manager - table in the manager
Sale items - by marking these as on sale - higher relevance/promotion to ’home page’
Volume Discounts
Front End
Shop by brand
Search by a price range or definable variant/TV
I know it is a big ask - but you did ask
But great idea and well done on it!