An update and data point.

We walked in through the airport doors at 5:06. Had one item to check in, so made our way to the priority line, first in line. There was a young couple waiting at the desk for the agent to return from I don't know where. Next line over (non-priority) there was an agent on the phone seemingly waiting on hold to figure out something about an elderly couple's Pakistani (pretty sure) passports. The priority line agent returned after about 20 minutes, and it looked like that young couple's passports were also not Canadian. Then she processed another group of people on whose issue she'd worked before we had got there. 30 minutes later, it was our turn. A line of about 15 people behind us had already formed. No one at non-priority. No Elites showed up either, thankfully (I presume they get priority over Priority).

Security took but a minute. At CBP, the little passport scanning machines were cordoned off. Might as well, there was nary a soul. We went straight to the CBP officer, sweet and short. Arrived at the gate area at around 5:50.

The Plaza lounge at YEG transborder was closed, understandably.