You're describing my phone 🤣

How does Lineage compare to Grapheneos?

Afaik Graphene is only for Pixels, so it's only Google Tensor CPUs. I would choose Snapdragon to avoid any possible backdoors (if we talk about real sh**) 😏. Tho Graphene is focused on security and privacy. Never tried it. I have one offline phone on Lineage - works smoothly.