Query regarding UK/AUS NES games

[The S]

Would NES games from UK or Australia work on a US NES? Or better still, a Retron 3? I've sleuthed about and found inconclusive answers, so I figured I'd go somewhere where someone probably has an idea.

[SparTonberry]

Different lockout chips, so they'll work if you disable the console lockout, or use a toploader which has no lockout.
Then they will work fine, assuming you don't mind any glitches caused by timing differences in PAL-optimized games.