In reply to ianstevens:
> as far as I know Viewranger mapping doesn't include DEM data as standard
Viewranger must have access to the DEM data, since it uses it for 3D presentation (or maybe only the desktop version does?). Whether it allows this data set to be interrogated to give the DEM elevation for cursor position, rather than GNSS elevation, I don't know.
OruxMaps uses DEM to allow 3D presentation of the map, and to give the DEM elevation when navigating.