NATO is not Physically intervening (actually they kind of did by providing military aide to Ukraine) is because they don't want to give Putin any excuse to diversify this war. This war, is still small compare to the scale of other war (Russia uses only 1/7 or 1/9 of national strength), which is for them and Ukraine being manageable. Any intensify of this war will be unpredictable, it could range from an all out conventional war (Which will devastate Ukraine and the Baltics), to WW3, to thermonuclear war.
On the other hand, NATO already say there are no base line for nuclear attack, launching a nuke , regardless how small is the yield in Ukraine, will most likely trigger NATO response, which again, would either mean WW3 or nuclear exchange.
Both side are crazy,, but not that crazy to wanted the world to end..
Name me another one?
There were like 5 or 6 Neo Nazi group in Ukraine, and Azov wasn't even in the top 3.