It's not something that's a choice. Annexation to the US will be something completely out of their control. It'll happen fast. Carney will try to do X thing, Alberta declares independence. Their government makes a deal with Trump in the next few weeks, bam. First Canadian territory and Canada can do nothing about it. They try to force their hand with military, but it'll last all of two seconds. Then once Alberta successfully secedes, Quebecoise soon follows. Bam, the rest of Canada has no choice but to break apart and make territory deals with the United States for protection, law, and resources. The Canadians have absolutely NO say in any of this and protests will swiftly be brought down.
Trump will tell them "Okay you can become the United Territory of Canada and you have to follow the Constitution" or some shit like that, and bam. Annexation complete. Aside from minor changes, the average Canadian won't know the difference. Life moves on.