I’m a Canadian citizen with Nexus. I applied for ABTC and was conditionally approved online. I walked into the Global Entry office at SeaTac airport one morning before a flight to ask how to book the interview. At first they were a bit confused if they could do the interview for a Canadian or not but one of the guys said they could. The “interview” was maybe 3 minutes max, and I was in and out in less than 10 minutes.