>Look ma, we made grandpa's genocide into a game for 5 year olds.
Both, but mainly it's because of a common enemy - the liberal-democratic west. Russia has very little in common with conservatives in the west when it comes to lifestyle (divorces, suicides, drugs, hiv, alcoholism, abortion are at record levels there - much higher than in most western countries) - but it promises "conservative values", hates liberals and delivers anti-LGBT legislation and that's enough for far right.
It's not unlike the nazi alliance with communism before WW2. Both wanted "liberal global order" gone.
https://en.wikipedia.org/wiki/Molotov%E2%80%93Ribbentrop_Pac...
https://en.wikipedia.org/wiki/German%E2%80%93Soviet_military...
And it started in 20s already: https://en.wikipedia.org/wiki/Treaty_of_Rapallo_(1922)
Soviet russia helped Germany work around the military restrictions that were placed on them after WW1.
The opposite lesson from WW2, where having genocidal right wing nationalists tended to start the wars which you would then lose. The RWNs in Ukraine are even cited in the Russian causus belli (yes, obviously that's BS and it's an unjust invasion).
RWNs in Europe also tend to be pro-Russia. Possibly because Russia is paying them, possibly sheer contrarianism. Either way it's going to be difficult to divert them from divisive, fictional "enemy within" anti-immigrant discourse to the real threat from Russia.