Volvo was not "offered half of Norway's oil". But there was indeed a large collaboration in the works. Norway would trade cash and the rights to three unprospected regions of the North Sea to Volvo, and would get 40% of the shares of Volvo.

The deal was declined by the Volvo general assembly. Even if it had been approved by the assembly, it would also need to be approved by the Norwegian Parliament afterwards, and it's not a hundred percent clear that would happen.

Here is one article on the matter. It is a bit confusing, because the main proponent for the deal (CEO of Volvo at the time) says the deal would have been worth $85 Billion. While the main opponent of the deal thinks Volvo made the right call because only one of the three regions had gas, and none of them had oil. Both sources are biased though, so it's a bit hard to know how true these statements are.

https://www.businessinsider.com/sweden-made-85-billion-mistake-2016-6?r=DE&IR=T

So it's true there was a major deal in the works which would trade rights to natural resources for Volvo shares. But it was a much more technical deal than simply "half of the oil for half of Volvo".