The HST number for Airbnb is available online from the government of canada at: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/gst-hst-businesses/digital-economy-gsthst/confirming-simplified-gst-hst-account-number.html
Using that link I found: 723689006RT0001 - Airbnb Ireland UC
To confirm that Airbnb Ireland UC is the correct Airbnb subsidiary for Airbnb Canada I referred to this webpage: https://www.airbnb.ca/help/article/2860
This approach might also work for Expedia, but I did not check.
