GrapheneOS has two officially supported installation methods. You can either use the WebUSB-based installer which we recommend for most users or the command-line installation guide aimed at more technical users. We strongly recommend using one of the official installation methods.
The command-line approach offers a way to install GrapheneOS without trusting our server infrastructure. This requires being on an OS with proper fastboot and signify packages along with understanding the process enough to avoid blindly trusting the instructions from our site. For most users, the web-based installation approach is no less secure and avoids needing any software beyond a browser with WebUSB support.