GrapheneOS is the best mobile OS. Even though the Graphene team has weird habits of communication which might be off-putting for some, the OS technically still is the most secure AND most private mobile OS distribution you can have on any phone. It's literally at the top, according to many technical and data protection experts. It's so good that Cellebrite can't crack it even with physical access, and some police in some country (I think it was Portugal) will assume you're a criminal for using it, because it's so secure and private and they can't stand the thought of someone fully utilizing their personal rights. Plus, it has great documentation and is easy to install. Despite it being so secure and private by default, it still allows you to shoot yourself in the foot by installing the sandboxed Google services and so on, if you really want to. So it can also be used like an off-the-shelf Android, just with some additional hardening and extra protections on top which you benefit from, but the benefit will be much smaller of course when you install and use spyware apps.