A direct link to Google Maps Directions, where the destination is provided as a coordinate pair, can be created with the following URL:
https://www.google.com/maps/dir//37.78133194213231,-122.43221998214722
However, when opening the link to the Google Maps app on mobile devices such as iOS, this throws an "unsupported link" error every time, whether accessed through Safari or Chrome.
Is there a workaround for this problem (documented here) ? Please note that a URL containing both origin and destination will throw the same error.