Entering the US it was still everybody off and line up. But the US side now has adequate facilities for any conceivable passenger load, with a long indoor ramp/hallway leading to inspection and a large seating area just in front of the inspection entrance. Plus a covered platform. We had quite a big load, probably between 50-100 people crossing (largest by far of any time I've been on the Leaf) and the end of line up was nowhere near the door out to the platform. I was close to the end of the line, BTW.I like the Grounded Life videos as a rule, however they said their arrival inspection "took about 15 minutes". Having done this trip many times, that seems pretty optimistic - perhaps "spun" to improve the experience? Perhaps things have improved since the resumption of the service. They did comment that they waited on the train until their car was summoned, which would be a new experience for me. Previously it was "everybody off" and line up on the platform with your luggage regardless of the weather. Some real world confirmation of changes by anyone having done the trip recently would be helpful.
Sorry, didn't ride it northbound, so can't speak to Canada where facilities are older and much more limited.
Car by car is how they've always done it in Vancouver. There the line up is outside and part of it is not under any sort of cover.