Can Mechanic interact with Shopify Scripts?
Yes, but in a very, very limited fashion. The usual methods of integration are off limits: Shopify Scripts cannot make HTTP requests, nor can they read metafields, nor can they be invoked by external callers – with one exception! According to Shopify's documentation on the subject, "you can schedule scripts to run during events using the Launchpad app".
There are some pieces of data that Scripts can read, which Mechanic has access to (customer tags, for example). This means that you could use Mechanic to modify this data, and then make decisions in your Script based on what's written there. For a complete list of what methods are available in Shopify Script, see their documentation. Not everything listed here can be modified by Mechanic (Mechanic cannot modify carts, for example), but many things can (customer tags, product tags, etc).