I’ve flown to WDW solo many times - no issues going thru customs. I have Nexus and I’ve went thru with them not even asking a question. I’ll report back next weekend with how it goes.
At least when flying out of Canada …you are still in Canada it you have issues at the “border” The one often seen in the news about the Canadian that got held ..if you just look at headlines you would miss that they were entering from Mexico, and on a Visa, not for pleasure. If you are denied entry, do not try alternate ways to enter. (I have a relative that tried this 10 years ago - they were denied at one airport, so tried another that they had flown out of before. Of course failed. ..which is also to say it you have a VERY old thing on your criminal record that is minor - get it pardoned before you attempt to cross while trying to take your grandkid to Disney

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