Hi @SheldonBina2
That is correct. In this case because the elevations are coming from Zeno Connect with a vertical coordinate system of NAVD88 in meters, once Field Maps supports vertical datum transformations, the app should be able to transform into NAVD88 in feet. However because Field Maps doesn't currently support vertical datum transformations, the elevations obtained from Zeno Connect remain as-is in units of meters.
This is why I suggested that since the elevation values themselves are accurate from Zeno Connect and all that's needed is a unit conversion, you could use the Project geoprocessing tool in ArcGIS Pro to vertically transform to NAVD88 in feet.
Or, if all that's needed is the actual elevation values themselves, you could use ArcGIS Pro to add the Z values from the features geometry into the attribute table and then simply use the Field Calculator to convert to feet. This of course doesn't update the values that are still part of the geometry still being in meters.
With regards to horizontal transformations, yes, this happens in Field Maps per the Location Profile configured and the datums/projections chosen between the GNSS correction service and the web map's spatial reference.
Thank you
-Kevin