What's the best way to geolocate a walkie talkie broadcasting on FRS channels using a UAV?
At ~460 MHz, a wavelength is less than 1 meter -- small enough to detect phase differences between multiple antennas at spacings that could be supported by a UAV.
From the phase differences between multiple antennas, you can calculate the direction to the source.  When you're far away, you could fly towards it.  When you get close enough to be mostly above the source, the direction vector will point to a spot on the ground, indicating the location.  Alternatively, if you fly around it enough to get significantly different directions, you can triangulate the location.  You'll have to get pretty close either way, since you can't expect the direction to be super accurate.