It would be nice to include in the repository some subdirectories for the most common platforms, containing scripts for creating a sysroot and cross-compiling.
I think that this is the biggest lack of the current tutorial: the provided instructions are easy to translate to other architectures as long as you don’t use a sysroot.
In any case I will be happy to contribute to this new repository!
EDIT: I just noticed this post from the ROSCon meetups