I do, yes. First on a Pixel 5 and then (and currently) on a Pixel 8 Pro.

The purely emotional icky feeling of giving Google money is far less important than the tangible security, privacy, and usability upsides of GrapheneOS on a supported device. But if that's important to you, just buy a Pixel secondhand, Google gets no money from that.

I wish more devices were supported too, but my understanding is that only Google makes devices that are both secure and open enough.

Article in German, but the relevant points from the GrapheneOS lead are all in english: https://www.kuketz-blog.de/weshalb-grapheneos-aktuell-nur-google-pixel-geraete-unterstuetzt/

One point about Samsung:

Samsung takes security almost as seriously as Google, but they deliberately cripple their devices when you unlock them to install another OS and don’t allow an alternate OS to use important security features