Where do I find a terminal lens for Unity?

Solution 1:

There is currently nothing that does exactly what it pictured above since, at the moment, a lens cannot define a content area like the one pictured in order to display (and update) the output of a command.

It is possible to press ALT+F2 and run commands from the overlay which appears. However, it is not possible to observe terminal output from commands run from this overlay.

Another option is to use CTRL+ALT+T as a shortcut to open a terminal window.