I know Lakemaster does have an Ontario chip, but only a handful of the lakes on the chip are high definition, so the mapping quality is not as good as you may expect, since many people assume any lake on there is HD. Meaning nearly all of the lakes maps on there are only 5 or 10 ft contours.
If you’re looking for LOTW, I believe they resurveyed or did a more complete survey a couple years ago and it is now included on the Minnesota chip, along with Rainy Lake and Rainy River. I would certainly recommend Lakemaster if you’re looking for the best LOTW map.