Graphene is a privacy focused OS and it only supports Google pixel (as Google pixel allows a relockable bootloader). If you value your privacy it is the best option afaik. I would do a fair bit of research on graphene since unless you’re privacy focused then it might be overkill and you’ll end up flashing a less restrictive OS onto the phone. Ive had some friends who couldn’t stick with it because it was more than what they wanted and caused too much friction