Hmm. 'tis a conundrum, as they say.
On the one hand, you have to keep your eye on the drone itself, so you can only glance down for a split second to check all's well before you have to look up at your drone again. Pros or people who fly a lot will have a VO (visual observer) whose job it is to keep an eye on the drone during those critical seconds when the operator's eye is down on the screen and off the drone. Typically that VO will have a pair of binocs or similar handy just in case they need to search for the drone itself.
Alternatively, they will have a second camera operator whose job it is to mainly look at the screen, and also call out if the battery's looking low, the drone's getting too far away, etc.
If you're flying legally on your own, though, you have to glance down and be able to get all the info you need from the screen in under a second. That means you really can't get a good look at what you're shooting, unless you park the drone in the air, then adjust your camera or admire its view, then find the drone again, hopefully still hovering where you left it.
What this means in practice is that you have to kinda sorta remember where all your data is on the iPhone and be able to get that information, glare or not, quickly and positively. That's practice. Where is the battery level? The orientation? Height? Speed? on the iPhone screen. Lastly, it's "what's the picture look like"?
When flying a real aircraft under Visual Flight Rules (not flying by instrument, i.e.), we're taught that we must multi-task between looking outside and around the aircraft we're in, scanning the instrument panel to check that all's well, and then operating the radios plus checking your charts (maps) and / or your GPS, doing the visual tour approx. once a minute, on average. That's a lot of eye movement. Then, when advised that there's other traffic in the area, one must quickly scan the sky, and report that one either has the traffic in sight, or not.
So it is, that when operating a drone with a camera, it's much the same procedure. Mostly look at the drone. Then once in a while glance down at the screen. If it's glared, no matter, catch it next time.
Of course, taking off into the wind and away from the sun helps you see the drone, but it sucks for the screen reflection. So yes, it's a compromise. My drone ops are usually two person flights, the camera operator has 3D
goggles running Litchi in stereo vision - we tried the head tracking and it worked well, but totally disoriented my camera operator. We also tried it the old-fashioned photographer's way - a piece of Duvotene black cloth, thrown over her head and behind her, and the front of it covering the top and sides of the screen. That works as well, but isn't so fashionable, let's just say.
Perhaps a good compromise is a long hood that tapers down near the eyes, so it's a dark rectangular funnel that has a decent amount of eye relief and space, and that's matte black inside. That way, glancing down into the tube will yield a glare-less image every time.
The fact remains, glare or not, that if you start watching the screen while you're flying, or checking the shot you're taking, or your map, altitude, whatever, for more time than you're watching the actual drone itself, then you have effectively stopped flying the machine in VLOS (visual line of sight) and are thus flying illegally.
Flying safely first, photos/videos second.
Always.
