I sure hope my Garmin works. I was planning to use it since the cell coverage/costs are so high.
Check your country lists now. You should be able to change the country to Canada. On our list if countries, Canada was not an option. Ours is about 10 years old and DH keeps saying he needs to update it. We ended up setting ours to the bridge, then used our smartphone after that for directions. I should have printed directions... and checked the ciunties in advance.
We went ti Belle River, Ontario a few years ago to visit DH mom gravesite but neither of us remember if GPS worked. I think not because we did stop at the local police station to ask directions to the cemetery. It was just a short visit while we were in Detroit visiting other relatives.

Oh well, I noticed that there is a currency exchange right after crossing the bridge in Sarnia. It says it has no fees and pays $1.25 per $1 USD. I don't know if we should bother stopping there or not. We are spending the first few days of our vacation near the National Park on Bruce Peninsula, so seems we might need Canadian bills some.