Hi @ivm512, glad to have you in the community!
Yes, you are correct. You can control external sensors using the GPIO of the Sparrow Node. The only caveat is you need to incorporate your usage of the sensor into the Sparrow Application Model.
You can checkout our Builder’s Guide to get a feel for the way applications are supposed to run on the Sparrow Application Host. We also have a line-by-line breakdown of our Diagnostic application.
Be sure to reach out if you have any further questions!
Zak