It’s no more or less made up then the white supremacist narrative in the US. Yes they are real, yes you can fill a football stadium with them,no they are not even a noticeable percent of the population thanks to how large both counties are. This makes it easy to fill a tv screen with Nazis and sell whatever narrative you want.

It's real, but it's only used for its anti-Russia symbolism. It's my understanding that they don't actually adhere to other parts of the ideology.

My understanding was that they do have a neo-Nazi militia that was incorporated into the official army, and they made at least some effort to clean them up a bit, after that. This happened because the militia rose up and started having significant success against the Russians in 2014 while the Ukrainian army was struggling, so there was a "the enemy of my enemy..." aspect. Whether they have any sway over, say, policy, I do not know.