I tried it. It's OK. I didn't want my main phone tied up with the drone though, so I switched to my old Note 8. Only used it that one day. It was a Christmas gift. Not sure what I need a drone for...lol
Not sure about the Note9. I fly my DJI Phantom 4 using an iPad Pro 9.7. Perfection!
I haven't flown with a standard iPad, I fly with an iPad Pro and it's pretty bright.I’ve flown with the iPad too but suffers in sunlight. The note seems to have the brightest screen amongst phones.