Europe will either be open or not. Whether you transit through LIS will almost certainly be a moot point. At this time it matters most where you come from. The EU categorizes countries as green, yellow or red. Canada is currently green. As long as Canada's Covid trend remains good (and there is no reason to expect a massive change in 2-3 weeks) we should remain green. Portugal is probably a safer transit point than FRA right now.

I'd stick with your current booking as your biggest risk will be whether you want to travel at the end of the month.

Biggest downside is the relatively long connecting flight you'll be doing to Berlin in a narrow body J.