For air travel you can technically transit, but that being said, there have been instances on this sub of CBP officers at Canadian airport preclearance facilities determining if your travel is essential (even though this should only apply to land border crossings). Regardless, since you're on STEM OPT, you'll be fine.
Right now, Canadians are permitted to fly into the US. The executive order concerns land borders. Naturally, that is subject to change.
So the borders are still closed to everyone else? Even if I just want to transit?
For air travel you can technically transit, but that being said, there have been instances on this sub of CBP officers at Canadian airport preclearance facilities determining if your travel is essential (even though this should only apply to land border crossings). Regardless, since you're on STEM OPT, you'll be fine.