The biggest challenge with a “parallel society” is probably the T&L aspect because physical goods crossing borders is a very arduous task and tenuous legally (immigration jokes aside).
But without a global supply chain of our own there’s no way to genuinely say we have a parallel system, beyond extremely localized (thing Amish or Mennonite areas).
I don’t have the solution yet but I know it’s a problem and I’m going to keep putting it out there until I meet the people who can solve it.
