When you look at the LED's on the rear of the craft and it flashes green red red, you only have 4 satellites, flashing green then red you have five satellites the flashing rapidly green you have satellite lock with 6 or more satellites. That's the only other way without tellimetry data telling you.
In Naza the lights are as follow. 1st flash green means gps mode. 1st flash yellow means Atti or non gps. Then....either of those followed by 3 red means less than 5 satellites, followed by 2 reds mean 5 satellites, followed by 1 means 6 satellites. All flashing green more than 6. So you could fly with green and 1 red flash, but I wouldn't. I like all green. Hope that helps. Jack
Do you still have the wifi module? If so you can reroute 1 cable to get telemetry on your Android device (works on IOS but you need third party apps like litchi).
If you don't have the wifi module, then your alternative would be mini IOSD with a 2.4ghz FPV transmitter and receiver to an analogue display. Must be 2.4Ghz FPV as your controls are 5.8Ghz.