Canadian-switched-to-American political geography has been discussed before. If we extrapolate the general consensus from
this thread to 2020, for example, most provinces obviously vote D. The possible exceptions are Alberta/Saskatchewan (the main point of contention, possibly some unholy mix of Montana, Colorado, and the Plains states); the immediate Maritimes, i.e. Nova Scotia and New Brunswick (which could either be an extension of ME/NH as a whole or of just ME-02); and Québec, where I'm honestly not sure where the Bloc voters would go party-wise.
Of course, this all assumes that Canadian provinces have been in the US for a while and their political evolution has followed those of the 50 states. If present-day Canada suddenly gets transplanted to the US, then obviously the RL polling mentioned above would indicate a Biden sweep.