Using rainx on drone as water repellent

[Andy9]

The issue is not only whether it will be OK after drying. There is a great chances for some aberrant electrical currents or short contacts in the electronics during the flight which can result in bad outcome. I can't see any reason why to fly in rain. In rain even visibility is so bad that you can loose orientation or can not see the obstacle.
The wet suit can offer some protection for sure but generally water and electronics doesn't like each other.