Hi @akros,
The first tutorial you point out is correct. And yes, you will need to cross compile the packages to be able to use them on Android.
Those instructions and this repo will help you cross compile a set of packages (with some limitations) so that you can use them on Android. Note that the packages are in Indigo; updating them to Kinetic may require some work. You are more than welcome to submit contributions to the repository if want. Also note that this doesn't include python packages. In other words, cross compiling the packages that are already available is rather simple (try following the instructions in the tutorial), but adding new packages may not be exactly trivial.
Another thing is that in some cases Android tools and infrastructure in android_core may be a bit outdated. The last Android API that is known to work is 25; for later APIS you may need to introduce some changes there.
I hope this helps. What you want can be done, but you will need a bit of patience and some work here and there. What packages do you want to use in particular? Can you edit the answer and provide more details?
Another option is to write a Java version for the code that you want. Depending on the package, this could be a simpler option.
EDIT: Android 8 & 9 support is in progress; see https://github.com/rosjava/android_co...