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Comments
So inserted images don't retain transparent background it seems. So can't insert an image of the arrow. You can draw one with the drawing sketch tools and modify line color and weight (see right arrow). Or model an arrow in a part studio (better yet configure it! For any size/aspect ration, can also scale that view).
Both the inserted model view of the arrow, and the drawing sketch, will show on top of the inserted png (the black arrow here is an image) if you send the image to back
I guess it works to a degree, but it is far from what I need.