I think they mean where half the screen shows a map and the other half shows Important Motivational Bike Stats (distance completed, speed, gradient, heart rate?

I think they mean where half the screen shows a map and the other half shows Important Motivational Bike Stats (distance completed, speed, gradient, heart rate?)... For the stats that OsmAnd can handle (e.g. speed, speed limit, elevation, ETA, you can configure what's in the pile of overlay boxes on the top right of the screen. I don't know if there's a plugin that could render the display as half-map, half-stats