How to show available drush commands per module with a drush command?
You can use the --filter feature of Drush. For example, you can use drush --filter=features to get all the commands available from the Features module, or drush --filter=views to get all the Drush commands available from the Views module.

You could then also pipe that output into a file if you wanted (e.g. drush --filter=views &gt; views_drush_commands.txt).

You can find the docs on the Drush homepage.