Awesome start I will look into the use of the key and see how it's handled throughout the entire process.
Regarding the python scripts, those are helpers that go along with the actual Hive Ledger app. They are only there for command line debugging. They have nothing to do specifically with the Hive Ledger app other than interfacing with it.
I'll still check out the Sia python helpers and see. Get public key is a helper that just returns the key from the app and optionally shows it to the user on the device. Nothing else