Everywhere in the world wifi signals are regulated. Max power is part of the regulation. Using a booster (most of them the cheap kind with lots of harmonics) is not a good thing in urban areas (which is what I'm commenting about). I do understand radio signals pretty well (having started building radios in the 70s and installing wifi networks since 1997), and a wifi booster is potentially problematic, especially when positioned in a flying drone over urban areas
You seem to live in the USA, FCC rules are pretty clear wrt wifi boosters (unless you have an FCC license, in which case you might or might not be in compliance). Using a booster puts you out of FCC compliance as a non FCC licensed operator
Antenna mods are completely different (and not an issue)