Why Plan 9?
Through a simple file system protocol, #9P2000 that you can use to create/export/mount/bind file systems and a consistent design where every service is controlled through a uniform API (a file system).
You can represent anything with a file system and once it's a fs you can both share access to it or mount it wherever you want.
Devsegment for example let you allocate a memory segment that can be also accessed (and thus exported) as a file.