alt Hacker NewsOne of the main criteria to differentiate "rants" from "correcting falsehoods" is proper citing of sources. In the case of Grapheneos, unfortunately I often see very few sources in what they post online.
(But, if you ignore the rants, that's a fantastic OS.)
GrapheneOS has plenty of evidence and they post it alongside their claims. They post it carefully though, and are willing to provide it to people upon request.