Oh yeah I know it’s theoretically possible. I’ve just never heard of it actually being done, for payments specifically, by banks. Using Google Pay doesn’t restrict you from also using any of those other use cases: you’re not giving anything up in terms of flexibility of functionality.
Yeah Garmin Pay is the equivalent on Garmin smartwatches. Unfortunately it’s not as widely supported by banks (at least where I live) as Google and Apple Pay are.