Hi,
I just found this article that might shed some light as to if or when the U.S. - Canada land border may re-open. If indications from health officials and governments and the article below is to be deemed accurate, it might take a year or so before there is any sort of free-flow.
Note: This may or may not affect filming in B.C. for Arrowverse and other U.S.-backed productions since it does not strictly prohibit air travel but the current quarantine provisions may / likely will still apply for air and sea as it currently does for land crossings.
"Outdated And Antiquated" - Ron Sexsmith, from the CD/LP/Download The Vivian Line. (2023)