We too are Canadian travellers, and I would have to suggest that you take into consideration the extra time that it will take for you to fly out of Toronto Island (under the same US bound travel scrutiny) to Newark, your time and money for a hotel night spent, then going through another check-in and flight etc, vs the small inconvenience of having a small carry-on, but only dealing with one flight and being in Orlando in 2 hours or so.
We have not flown out of Newark to Orlando but we have flown Detroit to Orlando and while there are many more flights to choose from and prices can be much better than Canadian flights, we currently prefer to pay the extra to fly from home. We find our time of travelling to/from the American Airport isn’t worth the cost savings to us.
Also, by the time you actually travel, almost a year from now, you may find restrictions have changed again.
I checked our airline for our trip in March and noticed they are waving any baggage check fees because of the reduction of carry-on allowances. If you fly two airlines, you may end up paying quite a bit in extra charges as well.
Just something to consider.