I figured out something similar, but I am having issues that the latitude of the coordinates seem to be wrong on macOS at least. Basically my markers appear a bit below the clicked coordinate (unless I turn off the toolbar, in which case they appear at the mouse location but we are talking about the top of the balloons, not the little bottom arrow part). I suspect there is an issue with converting the coordinates using .local caused by the height off toolbars and the window frame. It seems I get the correct latitude if I hide the toolbar and expand the window to fullscreen.

Your best bet is probably flang which is part of the LLVM project. Not really production ready yet, but should be usable when the arm64 Macs are released.