I assume you're "voting with your wallet" which imo is not an effective or worthwhile endeavor. What manufacturer is so much better than Google that they're actually worth going with over a Pixel with Graphene? The only one that I can think of is maybe Fairphone, but it only works in Europe and the extra cost would likely be better spent towards a donation to a project like GrapheneOS than a mediocre device that is neither private nor secure nor degoogled.

my primary reasoning for an android alternative is to get out of google's walled garden

You don't even need an alternative OS to get out of Google's walled garden. You can and probably should start doing that before you move to an entirely new OS.