You’re right, using sensorVars.compass.latestValue.heading or sensorVars.compass.latestValue.heading.degree does not work directly, thanks for reporting, I’ll file a bug ticket about it. However I was able to get it working on Android with the following set up:
I created a page variable compass to store the value, and used Get single compass value to set its value with the following formula: STRING(outputs["Get single compass value"].value.heading.degree) (the formula editor complains but you can ignore that). If you want to keep updating the value, you can add a loop with a short delay. I used the Component tap event for a button, but this can also be used to Page focus event to avoid having to use a button.