I think I've already said I've never paid, or paid extra, for nitrogen-filled tires, and never will. With Earth's air already at 78% I'm not sure how they get more in there than that.
Back in July 2023 I bought 4 tires from a place that claimed nitrogen was the only thing they used, no extra charge. They already had the best price on Wildpeaks I could find. They also make their nitrogen available to their customers for fills or adjustments as desired, for free.
So I've had months to experience the gas and I have to say it makes a difference with temperature changes. Temps were in the high 80F, and have gone down as low as +6F this winter. I set the tire pressure to 39psi when it was 35F one day and I've seen tire pressure go up by 2lbs and down by 2 lbs.
My wife's Eclipse, with regular air, has been all over the map with regular low-pressure warnings. She goes from 35psi down to 25-27 and I have to get to the air pump more frequently than the gas pump.
While I have to say I've been enjoying the difference I still feel skeptical and would not pay an extra fee for it. I guess I spent too many decades with just air.
My 0.02, YMMV.