As the workarounds have their limitations I created a small app optimised for Stark VARG. It lets you open the trail in a Picture-in-Picture window and keep it on top of the Stark dashboard. Once the Stark speedometer has locked Android navigation you can also open the app full screen for riding. More details:
headnorthgps.com
PS! The page footer has links to additional guides about workarounds (e.g. Google Maps in a PiP window). The guides need a bit more work before public sharing but if you’re interested the content is there (missing pictures and better formatting).