Pie should look homemade. Have you already tried to make a freeform pie?
You can make a pie in almost any kind of ovenproof dish. Then again, you don’t even need a dish. You can simply use the dough as a container for the filling, folding the excess edge in on top of the innards.
You can make it round, rectangle, square, triangle…in any shape you like. Just roll out your dough to the desired size and shape, and put it on a cookie sheet (on top of a piece of parchment paper or silicone baking mat). Spoon the pie filling into the center, leaving a few inches of edge showing, then fold the edges inward to cover the filling.
You can fold it in completely so the top is closed, or partially to leave some of the filling exposed. There will be wrinkles in the dough, making your pie looking “rustic”, which is, as you may guess, a euphemism for “messy.”