Option-N and Option-P (What are they doing and how do I disable or rebind them?)
Solution 1:
Thanks--the comments made me realize that I was barking up the wrong tree.
This shortcut was not a system shortcut but actually provided by Hammerspoon, specifically a feature (not a bug) of https://github.com/agzam/spacehammer, which is designed to provide convenient shortcuts for an "Spacemacs" workflow:
Other features
- Alternative App Switcher
Option n/p- Simple tab switcher for Chrome and iTerm
Option j/k
Quitting the whole Hammerspoon process gave me back those keys.