Is your feature request related to a problem? Please describe.
One of the things that sets gdu apart from i.e ncdu is the amazing preview functionality (v => Show content of file). I'm using it all the time. While searching/investigating log files etc, some of them are compressed. It would be fantastic if gdu had the ability to stream/uncompress ala zcat instead of just showing the binary data.

Describe the solution you'd like
I'd like to be able to navigate inside zip,gz (and potentially other formats, but especially formats that doesn't require a full decompression to disk) and preview files inside them.

Describe alternatives you've considered

• Create a wrapper around xdg-open (seems to be hardcoded, but doesn't do any good on a server environment)
• Better customizations for preview certain file extensions/patterns?