Can you force the destination to be LGA? None of the direct options will arrive there and then you are forced into a connection, which AC should be pretty efficient time wise.

If/when HPN or BDL come back, those could be additional options. Don't work for now.

What about direct flights to YUL/YOW/YYZ and then a separate economy fare to NY, that might get it to price more efficiently.

Also try checking pricing into PHL or BWI and take the Amtrak train into NYC. (PHL requires a local train transfer but is closer).