Timatic, the international tool that airlines use to determine visa and passport requirements, is super clear about NEXUS. If you’re worried about a rogue agent you can use the Emirates website to print out a copy:
https://www.emirates.com/english/pla...uirements.aspx
I don’t think I’ve flown AS with just a NEXUS card, but I have flown Delta and Westjet without issue (except that I couldn’t check in at a kiosk or online, both times an agent had to check me in.)