I've also looked into this operating system a while back as well when looking for ChromeOS alternatives as a GrapheneOS equivalent for PC, unfortunately to me it seems this project is just a virtue signal that they are contributing anything to open source so they can sell you their proprietary version. It's very bare bones similar to ChromiumOS and it needs to built from source as well as not enabling auto-updates by default. Another key feature missing is Android app support which doesn't even really make it a competitor to ChromeOS at that point, I believe their proprietary version rips the Android component directly from ChromeOS which is why they don't include the functionality in the open source version, which they've said that they're "working to replace it" for years. For now I don't think it's worth it to look for ChromeOS alternatives, especially sense Google's head of Android confirmed ChromeOS is just becoming Android which would open the door for GrapheneOS itself on laptops. I recently built a PC that I put SecureBlue on it based on some recommendations and to me it seems like a decent contender for existing hardware, which the project seems to be looking to become a kind of GrapheneOS of Linux which I'd recommend checking it out if it fits your security model.