“How America took out the Nord Stream pipeline”

Looks like the only 100% benefactor of this is Ukraine. Russia now must pump all its gas to Europe through Ukraine. And they are already at war with Russia, so there is no risk of escalation. And they have pulled other impressive stunts no one believed were possible, like Moscow cruiser, Kerch bridge, Engels airport. They kept it secret because didn't want to alienate Germany.

But would ukraine devote resources to do this sabotage, when they're actually short on resources? And where did they get the ship and the movement of troops/operatives to pull such a thing off? Surely, a rogue ship in the most heavily monitored sea would throw off alarm bells.

Not saying they can't have done it, but it would have required more resources than ukraine would spare imho. And if they have such resources, would they not use it instead to sabotage something else of more importance to russia? Such as their oil or gas fields that are still operational?