Thanks @jonh for looking up the thread. To create a local cache is what I had in mind in the solution sketch in my second post.
Good to know that the DEPOT_PATH can be set via JULIA_DEPOT_PATH (it does not appear in environment variables in the Julia doc, but only in the glossary of the Pkg doc).
To my understanding, --compiled-modules=no does completely deactivate the usage of the precompilation cache [1] rather then to force the usage of the available precompiled modules without any check. So, unfortunately, this will not solve the issues raised in my second post.