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.

You can always just check that a carriers bands are supported by the hardware yourself.

https://gsmarena.com/google_pixel_8_pro-12545.php

This seems very weird, as it shouldn't matter at all. Are you talking about eSIM support, or just 5G?

They may be something with different wavelengths for 5G, but I'm not the right one to answer on that one.

The Pixel watch supported carrier list also makes no sense, because for some reason the new carriers for the watch 2 don't support the first version?

They often don't update the list for older devices. The supported list is whatever it was when the device came out.

I actually don't know what you mean by "Google's allowlist" but the underlying carrier might matter more than whatever small "carrier" you want to go with. E.g. Telus, Bell, Rogers(/Shaw), Videotron basically run all of the cell networks and then lease them out to the small carriers (which they actually either own, or will eventually).

So if those big guys are on the list, you're probably fine (but I don't actually know how it works). You can google "{name of carrier} mobile network" to find out whose network(s) they're on.

Canadian here who used both small and big providers with pixel phones (3, 5 and 7 pro) bought directly from Google (not financed through the provider).

Not all smaller providers provide 5G but they all have LTE or LTE+. I had 5G working with my Pixel 5 without issue when I was with one of the large providers. I'm with a smaller provider now on my Pixel 7 pro and have no issue connecting to LTE(+).

But, you also mention the Pixel watch. I never used a watch with a sim card and I have to say that it is not always clear from the provider's website if they are supported or if they will provide a esim for them or not, and at what cost. This is something that looks a lot more straightforward when with Apple than Android.