NickelMenu is a mature project and perfect at what it does, we just have different goals. NickelMenu is designed to extend Kobo's stock interface. Cobalt is designed to be an app platform like Android has for example. I wanted app creators to just write their app logic and not build things like a UI toolkit for their apps, app lifecycle and rendering support (framebuffer drawing, partial eInk refreshes, touch input handling etc.), bluetooth handling, sensor and more. Anything launched through NickelMenu like KOReader or Plato have to implement these on their own.

AFAIK NickelMenu command actions spawn arbitrary shell cmds that inherit root from Nickel, we avoid it by running apps as separate unprivileged processes with declared capabilities like network, storage, audio, fronlight etc.

I also wanted to provide ability to quickly build apps with the SDK and our simulator to test apps on before putting it on the real device, an app store to get new apps over the WiFi after the initial USB install.

This was more oriented on making my life easier, say I have an app idea that I want on my Kobo tomorrow and how quickly can I bring it live on the device. The 'you can run apps' I wrote was meant to signify anyone can now create apps using the SDK without bothering about the device specific bits and publish them and install it via Cobalt's app store. I hope this clarifies things.