Every country has a far-right problem to some extent. You can make a compelling case Ukraine's is less significant than many other countries. Svoboda only has 1 seat in the Rada. A far-right coalition in the 2019 parliamentary elections only got 2% of the vote. Likewise in the 2020 local elections. Ironically Russia's far-right is much more influential in their politics. And most of the frontline fighting these days is being carried out by the Russian Wagner Group, which is a far-right military group.
"but Azov is part of the national guard"
Yes as part of the Minsk Accords to rein in the volunteer groups on either side of the fighting and have some government oversight. If you don't think there are Nazis in the US military I've got a bridge to sell you... that Air Force national guardsman was a real peach himself.
While United Russia is more or less a center right populist vehicle to support Putin I think you can make a very strong argument it has embraced far-right politics in recent years.
Also ftr the US has an explicit ban on funding Azov.