How Important was the German–Soviet Commercial Agreement in Allowing Germany to Successfully Invade Norway and France?

Before the war most of Germany's oil supply came from Americas. Supposedly Germany only had enough oil from three to six months after the invasion of Poland. They also faced shortages or rubber and manganese due to the Allied embargo (and as I understand even grain).

Does that mean that France and Britain could have just waited them out with minimal risk of a successful German invasion if the Soviets hadn't agreed to supply them with oil etc.

What about Romania? Was it supplying oil to Germany before the pro-axis coup?