I doubt you'll ever see generally heap compressed data in the way
you're thinking: postgres has a strong informal policy of not implementing features which are dubious and or excessively complicated with limited benefit, particularly if there are ways to handle this outside the database; there are various operating system level tricks that can cause a compressed file or even an entire tablespace (o/s folder) masquerade as a regular structures. So maybe you are asking for a feature we already have: CREATE TABLESPACE.
