Years ago I looked into GrapheneOS, and I ultimately didn't go with it because, at least at the time, they only supported pixel phones (specifically pixel phones that Google actively had security updates for). I realized that if I got that OS, I would be at the mercy of Google supporting the device in order to continue using GrapheneOS.
In the end I just opted out of the android ecosystem altogether and went with a flip phone that I used as a hotspot for an iPod touch (we only used over VPN with locked down DNS and nothing google related).
My privacy lasted about two weeks, because unfortunately Spotify was able to fingerprint that device to Facebook.
I would highly recommend LineageOS. Supports non-Pixel phones, some of them many years old (although now that I double check, the Galaxy S3 and OnePlus One aren't on the devices list anymore, I guess they do stop supporting old stuff eventually...). The OnePlus 5 is still supported and was released in 2017. For anything older than that, I guess I'd recommend looking into postmarketOS.
> at least at the time, they only supported pixel phones
At the time? They still are the only devices officially supported.
Having your freedom be tied to a handful of devices from Google, is a massive supply chain risk.