Of course there are Ukrainians who squatted in residences inside the prohibited zone. They probably are still there.
The Ukrainians don't dig trenches in radioactive soil unlike the Russians.
I saw this on a documentary years before this invasion. There were basically homeless people who were destitute and just moved into the abandoned homes inside the exclusion zone. They were not supposed to be there, but they were growing food to eat and living like there was no problem. I guess when you are desperate...