Sidekick DOES requires an internet connection, but currently only to log in. Once you're logged in you can run Sidekick uninhibited without the internet, so long as you don’t close the app.
If you are going to need to use Sidekick in a location that doesn’t have internet access, you can open Sidekick in a location that DOES have internet access then just leave it open until you are done using it. One option is to fire up a personal hotspot long enough to let Sidekick login, and then shut it down.
Please note that we do have plans for some features in the future that will require internet.