Just found in internet that fob programming process not available for Canada ???
How to Program a 2019 Buick Encore Keyless Entry Remote Fob Smart Key Step by Step How to Programming Instructions:www.programyourremote.com
I think method #2 worked for me, in that it responded exactly as the instructions described, and my original two remotes worked after the programming (but my third purchased remote didn't). Although I suppose it's possible the programming process didn't do anything at all, and the original remotes didn't get 'deleted', which might also explain why the third remote didn't work. The only way to know for sure would be for me to go through the whole thing again, and try making my original #1 the new #2, but I don't have the ambition for that.
(BTW I'm in Ontario)