You're right. But seeing requests that look like "https://duckduckgo.com/mapkit/?https://api.apple-mapkit.com/v1/directions https://duckduckgo.com/mapkit/?https

You're right. But seeing requests that look like "https://duckduckgo.com/mapkit/?https://api.apple-mapkit.com/v1/directions https://duckduckgo.com/mapkit/?https://api.apple-mapkit.com/......" there is little doubt that DDG forwards directions requests to Apple APIs.