Use the mapbox-gl-directions plugin to show results from the Mapbox Directions API. Click the map to add an origin and destination.
See the example: https://docs.mapbox.com//mapbox-gl-js/example/mapbox-gl-directions/
This shows how you can rotate a Google Maps SVG symbol icon around the lat and long of the marker. This does not work for some reason here, but works without a flaw and sails through Firebug without so much as a blink. Go figure...