And there's little doubt that if a country goes through a violent clash against corrupt government (see euromaidan), such groups would take the opportunity to gain standing. You can draw parallels to capitol hill events, or imagine what groups like Soldiers of Odin (the nordics) would have done had there been protests with bullets.
And when your country is invaded by a foreign nation, your army generals are not going to ask about the political opinions of those who are willing to fight for their country. A small group of nazis defending Ukraine from Russian invasion? So what. There will be nationalists standing in any country's army if they get invaded.
Talk about nazism is a mere distraction and something Putin's trolls would do. Please don't.