Here is what I can find about this mysterious fellow. I was wondering why a Russian was helping Ukraine fight Russia and how a Russian became a Neo-Nazi. He is part of a group of Russians that do oppose Putin and part of a group based in Ukraine called "Russian Volunteer Corps."

In 2001, when he was 17, Kapustin's family moved to Cologne, Germany.[5] According to Der Spiegel, the Kapustin family received a permanent residence permit as Russian Jews. However, asked about her ethnic background and her alleged Jewish origins by the Spiegel journalists, Kapustin's mother simply described herself as "a Russian woman"

During his time in Cologne, Kapustin was radicalised and became a well-known far-right figure who was associated with the far-right hooligan

His reach was limited in 2019 when Germany issued him a Schengen ban, or European-wide ban for “efforts against the liberal democratic constitution”.[8] This also applies to Switzerland.

via WIkipedia

If someone wanted to do an actual Nazi takeover of Ukraine, it would be this guy. Calling this guy a double edged sword is an understatement.