I have a complementary need close to yours (check on the field the "health" of water level management materials). So as I only need to show the location of the selected to check I am at the right place. I had to add the "maps" appearance to your example to show the default location on a map, and a read_only constraint set to "yes" to adapt and clarify the prompted message "show the Geopoint" instead of "show or modify..." .
The floppy icon remains on the map widget but the location can't be modified.
Here I can see the place I selected (the red circle) and my current location (the blue cross) 
