Best way to get Rect2 from a packedVector2Array polygon

I’m working with a voronoi diagram for a game and to keep other things simple I give the Polygon2D the points from the voronoi instead of normalising them first and translating the node.
Now there’s the shader and it wants the UV to be where the texture at 0,0 and not somewhere deep in the screen.

So, what’s the best way to normalise a PackedVector2Array? They only have 5~7 points each but I have hundreds of them.
I can’t find any function for this in the Pack.. docs, should I just loop through each Vector2 and build my Rect2 that way?

Ah, someone tried to get that feature into Geometry2Dusing expand but someone had a better solution. And once I have my Rect2D I can use Geometry2D:offset_polygon

https://github.com/godotengine/godot-proposals/issues/7333#issuecomment-1663488833