Accessing tightly-packed atlas UV coordinates from a Sprite reference

There seems to be no way of getting these besides going through the mesh UVs and doing a min/max. Even that might not return the original rect extents if the mesh is a polygon that is smaller than the original rect. Am I wrong?

 

https://docs.unity3d.com/ScriptReference/Sprite-textureRect.html

Like, call me old-fashioned, but.... why?

 

Oh I get it - if the sprites are tightly packed then rects are not valid drawing primitives because they may contain parts of other sprites.