While kylin isn't too far off from a traditional distro, officers will force you to install rootkits on both desktop/laptops and phones (JingWang). If you're caught later with it missing you will most likely disappear.
Red Star is horrifically oppressive and monitors everything you do. The GPL is of course ignored and very few changes are ever released. Trying to circumvent the restrictions causes the OS to self destruct. The few applications you can use watermark every file you create.
Long story short them creating linux-based distros is just an easy way for them to exert total control. It does nothing positive for the Linux or BSD ecosystem.