For what its worth, been using graphene for two months now on a pixel 5 and I’m still amazed by how well it works. Can only second this path as someone who is really focused on privacy and security. There are a few inconveniences (updates, app availability, gpush services etc) but those are all very worth it for me to sacrifice in order to be secure and private. I don’t think you’ll regret. Tons of second hand (new) phones on the market where I come from so should be easy to get going