Hitler wanted to exterminate Ukrainians too.==
Not exactly. If you remember Alfred Rosenberg? He wanted keep Ukrainians as pro-germanic tribe.
“...Regarding Ukrainians, he favoured setting up a buffer state to ease the pressure on the German eastern frontier, while agreeing with the notion that Russia could be exploited for the benefit of Germany.[42]...”
https://en.wikipedia.org/wiki/Alfred_Rosenberg
Ultimately the Nazis would have made the Ukrainians a source of slave labor.