There are separated bike lanes along Yonge between Davisville and Bloor.

Bloor has separated bike lanes that extend pretty far east and west. You can take bloor over to either University, Bay or Sherborne to go further south. Sherborne and University have a seperated bike lane, and Bay has a designated lane with a painted line or shared lane with cars depending on the stretch. Sherborne or University would be safer but may be a bit further to ride.

You can check out Google maps streetview to get a sense of the intersections and streets you’ll need to navigate. Also Toronto publishes a map of all bike lanes here https://www.toronto.ca/services-payments/streets-parking-transportation/cycling-in-toronto/cycling-network-map/

Bike lanes technically have a lower threshold for snow accumulation before dedicated plowing is triggered. In practice, you can’t always expect them to be clear enough to use. My advice is to test it as long as you can in the winter. Often you’ll find that you need to upgrade specific pieces of clothing (gloves, face covering, boots, pants etc) to have a comfortable ride for yourself. You might find that your bike needs alterations as well (fenders, fatter tires), but sometimes people opt to.ride a “beater” bike through winters due to the general havok it wreaks on the precision parts of bikes from corrosion and debris. Having a plan for how to clean your bike regularly in the cold weather is a must IMO.