Porsche started the whole Hybrid sports car era off with the 911 GT3 RSR Hybrid back in 2010 when they put the Williams Flywheel KERS technology in a GT3 and created a car with 200BHP more than its rivals that could also go further on a tank of fuel.
As for Nissan, they have a recent history of over promising and then under delivering and walking away.
In 2012 they jumped aboard the Delta Wing and all seemed great, but as soon as Le Mans was over they stole Ben Bowlby and all the Delta Wing designs away from the American based Delta Wing team, which basically stiffled any chance that the car could really make waves in GT racing.
Then they took the 2014 Garage 56 entry under the promise of a "full electric" Le Mans car, yet turned up with a "not a Delta Wing" that was a petrol engined car but with a motor and massive battery bolted to it that could juuuust about do 9 miles on electric power alone, yet claimed it was some sort of break through. That promptly broke down about 2 laps into the race and they threw the "not a Delta Wing" project in the trash.
Then in 2015 they anounced a full on manufacturer assault on WEC with the GT-R LM, promised a design they couldn't deliver, failed to turn up to any rounds other than Le Mans where they were woeful, and then threw that project in the bin too.