Bob, there is no such thing as bonsai tree seed. To describe seed as that is a lie. They are tree seed. If they germinate they will be saplings of course, that is what seedlings are. But they will not be any size in particular, they will become the size you want to grow them. So if you plant them in the ground for twenty years they will be big. If you keep them in a small pot they will stay small.
I did buy one of these a long time ago, they are a waste of time and money.
I have noidea what Jack Pine is, but you will be lucky if you get anything from it
Geoff.