In most contexts this is not true :
Global = Local
But in the case of iPKG there is no difference between a global , for all users, installation of packages or a local installation (scoped to a single user) from the perspective of the package manager.
Objects get restored in a library and stream files in the IFS. It doesn't matter to the package manager if that library is in some library list or not. So you can easily have one installation in a dedicated library for all users and have another installation in a different library with packages from different repositories (or the same) , f. e. for development purposes.
The client lets you decide where to put the packages, see parameter iPKG library
IPKGLIB. This is also the place where all the package management data for
this installation will be stored (all objects starting with
IPKG). But you can
also split this and have the objects located to another library, see parameter
I know that some sites like to separate data objects from program objects and have their files, tables, views and indexes in a different library. This is also supported by iPKG.