It's not odd, really. Pixels (unfortunately) have the most hardware level security features of any Android phone at the moment. That's why they only support Pixel. Graphene is working with an OEM to make their own non-Google device, though. Buying used does not directly support Google, as you stated.

Apple has already sold out iPhone users many times, their whole "we respect your privacy" marketing campaign was just that, a marketing campaign. They still sell your data and/or give it to the feds. You shouldn't trust any big tech companies, ever.