If you want to get just the basic out of the way, I know they're a real company at least. They've had some mainstream media attention already. I'd recommend you read about them first.

We are aware they donate to us and sell devices with GrapheneOS preinstalled. That is just something they voluntarily do. We have no say in that.

Use what you think fits for you. I don't make a recommendation for cellular network providers. Not using the cellular network will always be the best option, but that trade-off isn't fit for everyone.