Classification between sale of products and providing services was carried out by the Court of Justice of the EU in the Polish C-282/22. (P. w. W. Dyrektor Krajowej) case.
There is no doubt that the customer mostly requests electric charging, so refuelling is a product sale. Although many convenience services might be attached to this (e.g., parking is a calculative factor during charging, it is possible to reserve an appointment for the charger in advance, technical support can be requested, payment can be made via web interface), qualification does not change.
It also does not matter that charging is not based on the physical unit of electricity, but on the time required for charging.