I bought mine outright and wiped the Pixel version of Android and am pretty happy. To be clear, I wasn't trying to avoid giving Google money ... I just wanted a phone and operating system that I felt like I had control of, without having a ton of bloatware and spyware pre-installed by the vendor etc.
That's correct. It's my understanding that this is for two reasons:
1) google opened api/support for verified boot on the pixels (so you can tell if a border agent hacked your grapheneos phone, for example)
2) it's easier to support fewer phone models (given they are not a large team)
I bought a refurbished pixel 3a last year for a little over $100 and have been thrilled with my grapheneos experience. I don't run google play, but it is my understanding this can be done in a sandbox (allowing for more privacy than usual).