Vancouver YVR getting to quarantine with toddler

If you have money to spare, consider using a "town car service" (also sometimes called a "limousine service", though it will not necessarily use a "stretch" limousine). These are services who will dispatch a car & driver to meet you at the airport at a specified time. They are often used for corporate travel and for peoples' special events, and so are more accustomed to fulfilling special requests, such as a car seat. As an added bonus, you will not have to deal with flagging down a cab, explaining where you're going, and worrying about the fare, as all of this is generally worked out when you're booking the car in the first place.

The downside is that it is generally more expensive. One firm I found lists a flat rate of 85 CAD for a transfer from YVR to downtown, and the car seat request may cost extra. In contrast, regular taxicab fare usually runs 35–40 CAD plus a gratuity, so around 40–45 CAD total. I'm not sure what Uber/Lyft fares usually are, but I would expect them to comparable to a taxicab fare.

We use foldable car seats for travel. I always take them on a trip in case a taxi doesn't have a child seat or booster. Due to the adjustable seatbelt strap, it is definitely safer than no child seat.

Price is not much more than getting a limousine, but you get to keep it.

An option to consider is one my son & daughter-in-law came up with for traveling with their small kids:

Using a bungee cord, he attaches the car seat to a foldable luggage cart. He straps the kid into the car seat using the normal belts, then drags the combo through the airport. Upon reaching their seats in the plane, he unstraps the car set and puts it in the kid's seat (using the airplane's lap-belt to hold it down), folds up the luggage cart and stows it overhead.

For the younger one, who is booked as a "lap child" and doesn't require his own ticket and seat, they either gate check the car seat (and luggage cart) as they would a stroller (i.e. they get it back on the jet-way right as they exit the aircraft), or the flight attendants will find a place for it in an in-cabin closet. If your airline can't/won't gate check the car seat, you could at least take it with you as checked luggage (be sure to secure all the straps so they don't get caught in luggage handling equipment), since reason would dictate that you'll want it for the ride to the airport as you leave your current location, and you'll want it for travel around Vancouver even if you don't immediately have/plan to purchase/rent/lease a car.

This makes toting the kids through the airport easier, as they're both strapped in tight and are on wheels, helps contain the older one (who can be a bit rowdy) while in the plane and gives him a good view out the window, and has the added benefit of having car seats for both of them available immediately upon arrival at their destination.