“AphyOS is based on an open source version of Android, called GrapheneOS.”
(citation from here: https://www.techcircle.in/2023/01/16/swiss-startup-apostrophy-to-present-privacy-centric-android-based-aphyos-at-wef )
Furthermore: 'A number of mobile phone industry veterans working on a Swiss startup, Apostrophy, is set to present a new privacy-centric smartphone operating system, AphyOS, at the World Economic Forum in Davos. ’