Up to 15 levels of organizational hierarchy plus lots of flexibility in how you structure it.
Are devices correlated to employees and organizational structures?
Yes. Once you have your org structure configured, you simply assign your entities to the appropriate hierarchy level.
Given a data source that provides employee IDs with their supervisor's ID, and logic that can determine an asset's primary user's ID, can visibility be given based on org chart? For example, could I see the risks for workstations of those who report to me?
Yes. This can be done two ways:
Reporting: Create a query that pulls the user's manager from the user record along with all assets those users own and the associated risk of each asset.
Model Manager as a custom attribute. This all comes down to how you model your organizational structure and how you prefer to keep your data in sync.