Chris from Kinvolk here. Happy to see you're having success with Flatcar.
We, of course, agree that CoreOS Container Linux was a huge success. The uptake that we've seen in Flatcar usage, especially since the CoreOS EOL date on May 26th, has been extraordinary. So from what we a can see, the market is there for a minimal Linux for containers and and we're happy to continue filling that need with Flatcar.
I'm not exactly sure what you're asking. But Flatcar Container Linux is completely open source. In fact, everything we do at Kinvolk is. We do not build open-core products.
That sounds really interesting!
I currently work on a side-project which is a distributed application and I plan on incorporating kubernetes/cloud-native into some of the core concepts, so I will check it out once I'm at this part of the implementation!