Bad Elf makes a GPS receiver that plugs into the lightning connector on your iPad and doesn’t use Bluetooth. I used one for years until I lost it, so I bought a new iPad with built-in GPS. I suspect the Bad Elf GPS may be a more sensitive receiver with better signal to noise ratios than the receiver in my iPad. I also have a Dual XGPS 150A, but I have not tried it with the Spark, since I now have a built-in GPS. (Don’t need another thing to carry around and lose!)
Yes, the iPad is much more reliable than my Android Nexus 7 or Crystal Sky. My iPad Air 2 is much faster and has never crashed running dji Go 4. But you can’t beat the much brighter display of the Crystal Sky Ultra, so I often use it instead of my iPad.