The Nav map is North America wide so that should not be an issue. 2 years ago I bought a new Tacoma out of Oregon (via a friend) and exported it to Canada with 100 miles on it. While Toyota USA would not sell me a new vehicle I was able to buy it used from my friend. The Bumper to Bumper warranty is transferrable and honoured at all Canadian Toyota dealerships. As for certification, I had to acquire 2 inspections, one Federal and one Provincial. The Federal one was to insure the DRL's are not switchable and stays on full time and the speedometer shows both Imperial and Metric scales (MPH and Km). If you look at your speedo you will see 2 scales, albeit the metric scale is in smaller font; that's okay. The Provincial inspection is for safety because they assume it is a Used car. Naturally, the Taco passed in flying colours so it was more of a formality in my case.
For the Highlander I bought it locally because there is no price advantage to import from US. The Cdn cars are spec'd a little different from their US counterparts even though the cars all come from the same factory in Indiana. When I compared apples to apples, factor in Exchange rate (10%), cost of inspections ($800) and cost of modifying DRL's ($300), it is a wash and no difference.
The other obstacle this time around is I wanted to trade in my Tacoma which would have been complicated if I didn't do it locally.
So in summary, the importation of a Toyota from US to Canada is not a huge problem. However, crunch your numbers. I don't think the time is ripe for doing so with a Highlander. The only advantage I see is the US cars are available with 1 extra colour choice, the Shoreline Blue. Also, in Canada exterior colours available with the Almond interior are limited to Blizzard Wh and Jade; the only exterior colours available with the Ash leather interior are Black and Pre Dawn Grey.