You are putting the dividing line between buying 1 and 2 items. Why not instead put the dividing line between "buying some items" and "not being able to do it just by buying any number of items"?
Then by that definition, all entry points are primary. Following that reasoning, supermysterychunkhax is a primary entry point, because I could just go buy a Cubic Ninja copy and a Pokémon Super Mystery Dungeon copy, then get ninjhax running in order to run the supermysterychunkhax installer.
Why would it matter that I had to get Cubic Ninja to get supermysterychunkhax running, huh? ¯\_(ツ)_/¯
As it was already said, the meaning behind primary is that you only need the game or app and NOTHING else (not talking about Internet access, of course). Secondary means that you need something else on top of the game or the app in order to get homebrew running.