Making a custom OS for a gaming console is relatively easy compared to an actual, full desktop. You just need to allow games to access rendering directly (DRM

Making a custom OS for a gaming console is relatively easy compared to an actual, full desktop. You just need to allow games to access rendering directly (DRM or equivalent) and you make an "app" for your store that'll also launch the games. FreeBSD was chosen as the kernel so that Sony could keep it locked down and not share the source, no other reason.