I use Celestron Nexstar mount with it's GPS. When I connect from Ekos using INDI I connect successfully, and I was expecting to get GPS updates as well, but I found the indi configuration uses GPS Simulation and gives abnormal coordinates. The plate-solving was not able to apply the coordinates to the mount n this GPS location.
Any idea of how to use Celestron GPS coordinates, or shall I buy external GPS?
The driver uses whatever time/location reported by the handset. Do you have GPS Simulation driver added? If not, then you don't need to worry about the "GPS Simulator" field as it's just the default value there, but if there is no GPS driver connected then it doesn't matter.
If the Celestron mount has a GPS and the GPS is set as the location source in the mount then the location provided by the mount will be GPS - at least once the GPS has connected. The mount time will also come from the GPS.