Nitrous complements high compression engines well mainly because of its extremely cool intake charge temperatures. This cooling effect wards off detonation when run on pump gas in high comp engines. Nitrous also effectively carries more oxygen into the combustion chamber without compressing air like turbos or superchargers, because of its chemical makeup, so combustion chamber pressure before ignition can be lower, further reducing the chance of detonation.
All engines make more power with higher compression ratios (to an extent), the only reason you see low CRs is in turbo/super engines is so that they can run on pump gas without detonation. I've never seen a N2O engine with low CR, it just wouldn't make much sense.