Change device initialization options externally

Hi there,
a few questions for make more clear the prepare-device flow.

Is it possibile setting the key

  • device-service.url
  • device-service.headers
  • registration.proposed-serial
  • registration.body

outside the prepare-device?
I know that snapctl work only within a snap, while outside snap it is necessary to use snap command to set up key value.
What is the snap accountable for the previous keys - snap command need of snap to apply?

Can the process to get serial assertion on a board be triggered outside the prepare-device hook?

Thanks

the process is triggered automatically at first boot, prepare-devices doesn’t trigger the process, it is called from it, and the process will be retried with backoff until it succeeds

the keys are on the gadget snap itself

I try :

snap set fingbox  device-service.url="https://device-service"

and I receive :

error: cannot perform the following tasks:
- Run configure hook of "fingbox" snap (snap "fingbox" has no "configure" hook) 

fingbox is my gadget snap.

one cannot set configuration values on a snap externally if it doesn’t have a configure hook ; docs