Hey @ashmaroli I am very sorry for the super late response, I haven’t been in touch with the jekyll talk forum so I missed this reply 
I agree that in the current form, it consumes GitHub APIs. I myself have been figuring out ways to add native jekyll support to the devices.
Regarding the JRuby implementation, I am not sure that way would work or not. Because Android doesn’t run JVM under the hood. It’s based on DVM, which can understand instructions from .dex files (Dalvik Executables).
When we write Apps in Java, the code gets converted to byte code, and then the byte code is compiled to the .dex format.
But there’s a possible solution: Android provides NDK for native C/C++ development on Android. The termux team has patched the CRuby implementation and successfully compiled it using NDK, ready to be used on the devices. The package also installs the gem package manager which I hope can be used to install jekyll and bundler on the device.
Once we have the compiled .so or .deb files we can call functions inside them using Kotlin/Java code, this is possible by NDK.
I got in touch with the team, and they could assist me in compiling ruby for JekyllEx. I think I can take this task as a hobby because I would learn a lot about underlying linux in Android and other packaging things in general. I’ll keep you posted on the progress.
Thanks a lot!