Damage in some form is distinctly possible. You could also die even in the event of rescue or recover fully with a story to tell. As with anything that leads to death by hypoxia--or more broadly, literally any attempt to end your life--there is a chance of damage in survival. N has no specific antidote, but there is supportive care which is highly effective in of itself even in absence of antidote, and shouldn't be underestimated. Chance of survival is strong. The presence/degree of damage would depend on a multitude of factors (time frame, dose, purity/degradation, individual physiology, knowledge of your situation via admission/evidence at scene, dumb luck, blah blah) that would make a true reliable prediction impossible. One man's long nap/weekend ER getaway is another's PVS. The notion of a quick, painless, highly lethal method that is simultaneously also guaranteed to leave you fully intact in the event of failure is purely mythical and a form of wishful thinking everyone would be well advised to part ways with. It's why it is constantly advised to do everything in one's power to isolate and minimize the chance of discovery and interference for an extended period if serious about attempting.
People love to say this (you'll be a-ok in event of failure) about SN, for instance, and it drives me nuts. Just...no. Sure, maybe. But if "rescued" at a late point where the methemoglobinemia has had a chance to really work its magic, then Humpty-Dumpty may be missing a piece even if he lives. It's a prime example of insidious misinformation in the form of a comforting idea that tends to plague this forum. It's obvious why the binary of total failure in the absence of total success would be appealing to anyone, but this (probably) isn't a video game. I know this may not be what you were hoping to hear and sorry for the tangent, but literally any method carries that built in risk that one must weigh things against. There are a few N survivor anecdotes here that can be found via search. Most reported no lasting adverse effects at the time of posting, iirc.