Usually, fin executes in the context of the current folder (project). With use of aliases you can have fin execute in the context of another folder without navigating to it.
When you start project for the first time, an alias is created automatically for that project.
cd ~/Projects/demo
fin up
Now you can execute commands for demo project from anywhere:
fin @demo status
fin @demo stop
drush will also work properly:
fin @demo drush updb
You can also create a custom alias that would point to an arbitrary folder, for instance to point to a Drupal sub-site:
fin alias ~/Projects/demo/docroot/sites/subsite demo1
You can use Drush aliases along with fin aliases. To execute status for @dev Drush alias of the demo project:
fin @demo drush @dev status