I can’t speak for Canada but at least here in the US, I’ve used every Pixel on any carrier I wanted. And most of them were small ones. Straight Talk, Ting, T-Mobile, and one more I can’t even remember the name of.
IIRC, the “allowlist” stuff was just “known carriers that use towers that are compatible with this phone.” As in, different carriers use different “bands”, or frequency ranges, for their transmissions. Your phone has to have hardware support for those bands. So the “allowlist” is really just “we know these work.” I’m pretty sure neither Samsung nor Google will stop you from using an unlocked phone bought from them with any carrier that’ll accept it. These days, I just stick a SIM (or eSIM) into my phone and just go.
If you can afford it, I personally highly recommend just buying two USB-C hardware Yubikeys and storing it on there. Built in back up and if you put it on your keyring, it’s always nearby. You can still use your phone to access the code as well.
Not exactly super helpful for solving this problem but since you’re already going to have to reset or get new accounts, it’s a good time to switch over if you’re interested.