While it is certainly possible to surrender to a munition or an aircraft, I don’t believe surrendering to either are protected as the one taking in the potential prisoner has no reasonable way to control the area and extract the one surrendering.

The unfortunate reality is the Russian soldier had plenty of opportunity to grab a white flag and walk west, but instead decided to man the line all the way until he was feet away from a munition sent to remove his presence from the country he invaded.