Apple Watch Ultra: GPX navigation without iPhone?

GPX route navigation on Apple Watch Ultra without an iPhone is possible, but the native watchOS approach is more limited than what Garmin offers. Here's what's actually available:

Natively, watchOS has a Compass Waypoints feature and the Compass app that can show your heading and saved waypoints, but it does not natively support importing .gpx files and displaying them as a navigable route on a map. The built-in Maps app on Apple Watch Ultra can give turn-by-turn directions, but it requires an internet connection (or iPhone) for map rendering and routing.

For standalone GPX import and offline navigation, your best option is a third-party app. WorkOutDoors is widely considered the best option for this use case on Apple Watch Ultra - it supports importing GPX routes, displays them as overlaid tracks on an offline map, and shows turn-by-turn guidance directly on the watch face without requiring the iPhone to be present. It does require a one-time purchase but there's no subscription.

Backcountry Navigator and Komoot (which has a watch app) are also options, though Komoot does require a subscription for full offline map access.

For the workflow you described - importing a GPX on the watch and navigating without the iPhone - WorkOutDoors is genuinely good and approaches the Garmin experience more closely than anything Apple provides natively. You pair it via the iPhone app to load your routes initially, but once loaded they run fully offline on the watch.

It is a legitimate frustration that Apple Watch Ultra, marketed as an adventure watch, doesn't support GPX import natively the way Garmin does out of the box.