Due to the current Canadian restrictions travel restrictions for individuals in Omicron hotspots, they will need to "Obtain, within 72 hours of departure, a valid negative COVID-19 molecular test in a third country before continuing their journey to Canada" as stated here: https://www.canada.ca/en/public-health/news/2021/11/government-of-canada-introduces-additional-measures-to-address-covid-19-omicron-variant-of-concern.html
To not have to enter a country and deal with potential quarantine issues due to being in an area with a variant of concern, it looks like both Zurich and Frankfurt have covid testing inside the airport (https://www.flughafen-zuerich.ch/en/passengers/news/corona/general-information and https://www.frankfurt-airport.com/en/flights-and-transfer/covid-19/coronavirus-testing-at-the-airport.html respectively).
I've asked Canadian Foreign Affairs and they recommend Frankfurt, but I've been unable to confirm if the tests are able to be done in the international areas of the airport. Zurich is a bit more clear in that it is in a transit area, but on their map it appears to be behind a customs gate.
For Frankfurt, is there testing in transit areas or only outside the transit areas? And is there any information about where exactly these tests are conducted (i.e. international areas)? Has anyone had experience with them?
EDIT: I've contacted Frankfurt and the test providers, and they've been unhelpful, only saying to contact the medical center. The medical center doesn't have a number only email, but they have yet to respond.
EDIT 2: I've added an answer since I've gotten a lot more information between asking this question and now.