Wahoo Mini. About $99

Comes with a speed sensor (wheel mounted) that will allow the unit to function as a basic bike computer without needing a smartphone connection to be present and running during a ride.

But note that as Wahoo requires the companion app be installed on a smartphone to do an initial setup, that app can then be used to connect to the Mini and accesses the phone GPS receiver. That then gets you a position map and GPS track that can be uploaded to Strava, RWGPS, if you use them as fitness trackers. It does not, as far as I can determine, allow you to generate a route from a 3rd party such as RWGPS to have a pre-planned navigable route to follow. The Bolt, Elemnt, Elemnt Roam and assorted Garmins, Lezyne and Polars do all this but are more expensive.