Thanks, well, as far as I know iOS still has very limited support for physical controllers. I know some bluetooth controllers might work, but as far as I know it is not possible to connect an RC radio to iPhone/iPad devices, which makes it less appealing for a FPV simulator in my opinion. (Most people would just be able to fly using touchscreen controls, which is not ideal for FPV practice...)
If anyone has other information regarding physical controllers please let me know.