thanks for the input!
I just haven't figured out, what happens if users on my small instance would join larger communities in other instances. does the small instance needs to mirror or route the traffic to the other instance, or is this only done through links and on the small instance is really only the stuff local users generated?
when you say fully isolated from the Arch libs on the system, means I have all dependencies of the installed programs doubled on my system - only if needed of course. so they can't share the same liberates already provided by the Arch/base system?