While the crust doesn't have to be on both sides, there does still need to be some kind of crust. So that disqualifies lasagna and moussaka, at least in any form I've ever had them. It also probably disqualifies most if not all casseroles, since they don't have a crust, or at least I wouldn't call it that. (In my experience, many casseroles have no breading. But, in those that do, it's usually either mixed in with everything or is lightly sprinkled on top.)
I wouldn't consider a toasted sandwich to have a crust because to me a crust is more of a hard pastry layer, not a fluffy piece of bread which has been browned.
Though that is a bit of a gray area. If you were to take some fluffy white bread, get it wet, and mash it down into a layer that lines a pie pan, and then put some filling (fruit for example) in it and bake it, and if the bread all hardened together into a cohesive outer shell, then I suppose I'd call that a very unconventional pie.
Just to make everything more complicated, there are deep-dish pizzas that have a very pie-like form. There's crust on top and the bottom, and they are cooked in a pan that resembles a pie pan. For example, this: http://winespiritsbeer.blogspot.com/2013/09/beer-crust-deep-... . Compared to a flat pizza, I think those are more deserving of the word "pie" not only because there is a crust but because the ingredients are more of a filling and less of a topping.
Another question is whether a (baked) calzone or empanada is a pie. They certainly meet most of my criteria, so maybe I'd have to say they are.