Z is just an easily painted symbol to differentiate the Russian forces from the Ukrainian ones, since both use same military equipment which is hard to tell apart.
Other than that, there is no significance to the symbol.
You want to see the real Nazi symbols? (btw, the Nazi emblem is actually called the Hakenkreuz, while the Swastika is a Buddhist symbol that's existed for millennia)
The Wulfsangel was a symbol used by Hitler's SS:
reportingradicalism.org
You'll lie and tell me that's not Nazism, but it's very clear that it is. Even the Ukrainian word for "nation" is "natsiya" and a nationalist is called a "natsi"
So Nazi is not some taboo word in Ukrainian -- it just means someone who is nationalist and supports their nation.
There's no strong barrier or dividing line between their nationalists and Nazi groups, the latter being just an extent or degree of nationalism.