Novel project and very restrictive. Lots of headdache if you need to go beyond Flatpaks. It attempts to apply Android's sandboxing security model to Linux, which is ingenuous but still very early. Good for a netbook style computing though. Qubes is the gold standard, and easier to use than it seems but has major performance overhead. Kicksecure is less secure than Secureblue and has a different philosophy, mainly focusing on being a hardened traditional Linux experience than emulating Android's security model. Its got great features if you need plausible deniability with Live mode, Qubes and Secureblue lack this feature. If you find Secureblue too restrictive, please try these others before going back to a less secure distro.