There is often quite heavy GPS jamming or spoofing. Also in some of the published videos I think you can see a "no GPS lock" status message - but maybe they just did not bother with GPS if all the drones were manually piloted anyway.
Yes, I assumed they didn't need GPS because they knew exactly where the trucks that were the launch sites were to be placed and they knew approximately their targets would be sitting on a certain section of airport tarmac. The pilots would have had a detailed satellite photo map of their entire route until visual target ID was possible. While GPS was probably partially jammed, that deep in Russia I doubt it would have been as severe as near the front lines. Plus there wouldn't have been heavy jamming of the local drone control frequencies because they weren't expecting a drone attack there.
To me the more interesting question is how they managed sending the real-time video feeds and control data. Since the trucks were mobile, I assume it had to be via a bunch of mobile phones signed up to Russian service providers since Starlink doesn't work inside Russia. To reduce latency, I wonder if the phones were connecting to a covert site in Russia which had a high-bandwidth wired link, maybe a front company established for the operation with servers and broadband internet connections.
