I’m also interested by an answer to @fhenryco 's question. In Onshape the UTM is also read only and a simple image:
https://cad.onshape.com/documents/6626b842adca229e69544ad1/w/89ac2637f82d915f22c2bcd0/e/f889952d4857145c2e9ec6bf
I also can’t find any gerber file very useful to manufacture such a PCB.
Pierre