The CP’s still work on drones, but you need to plan your shots accordingly to get the maximum benefit. Let’s say I want to fly up a section of stream, or across a lake and gimbal up to reveal an epic mountain. In that case, from the ground I’ll look through the CP in the same direction as my planned flight, rotate the CP in my fingers until I get the desired amount of polarization, and then mount it on the camera at that angle.
Of course this doesn’t really work if you are going to be flying in various directions at various angles relative to the sun, but in the 2 examples I gave above it works well. Same goes for glare and glint off rocks and foliage.