You're not even obligated to open-source or contribute changes. You simply must offer source code to anyone you distribute your combined work to.

For instance, if you sold these cameras at Walmart you'd need to provide a URL to source code on the box, or a mailing address where someone can write you a request.

If your company just manufactures and installs these on its own campus, you haven't distributed them, and you needn't contribute your changes.