Pripyat and Chernobyl are in Ukraine :)

There are (or were?) guided tours, but for a really good view of what it’s like there, I recommend Shiey’s Journey Across Chernobyl Exclusion Zone.

He’s a Lithuanian YouTuber and thrill-seeker who illegally went there and had to run from security at one point, too. He found lots of signs of other “Stalkers,” including a group in the flesh that invited him for dinner.

While the background radiation levels aren’t exceptionally dangerous and people do live in the exclusion zone, there are a large number of radioactive hotspots that could be extremely dangerous. They’re small pieces of the reactor core that were spread around by the explosion, and they’re extremely radioactive still. If you inhaled one or if you were to eat a plant or animal that had eaten/absorbed one it could do a significant amount of damage to you. Kyle Hill has some really good videos on this topic.

Kiyv oblast is not Russian last time I checked. The bears, wolves and workers might have a bone to pick with you though.