Just created an account to support this.
I don't care what the feature/function is called - I just want a simple list that I can add a *.domain space to.
Having a domain on this list should result in every new session to this domain space being created in an isolate process that cannot bridge information from other sessions' open or cached data.
The private window option is insufficient as its far too easy to invertedly open sites you want isolated within an existing shared session.