Was there a secret (another) agenda behind the Ukrainian Famine/Genocide besides socialism?

No secret. The Communists wanted the Ukrainian farmers to collectivize their land into huge communes run by the Communist bureaucrats. The farmers would be forced to turn over everything they produced and the bureaucrats would give them back just enough to survive on until the next harvest season. In other words, they'd be turned back into serfs with Communist bureaucrats telling them what to do instead of aristocrats. The farmers resisted this plan, so Stalin took all the food, and didn't give any back. It led to the m starvation of between five and seven million people. Welcome to utopia.