Why not simply parent the item you want to rotate to a node that's aligned with the parent you want to rotate around. With that, you could simply rotate that parent node as needed.
So, if you have something like this:
Parent
Position2D (you want to rotate this around Parent, without rotating Parent itself)
You could do this (for example):
Parent
Node2D (position this at the same location as Parent)
Position2D (the node to rotate)
Now, to rotate Position2D
around Parent
, just rotate Node2D
as necessary