The only way how DanNote can do such thing is to write a software that will analyze GPS location constantly and instruct block producer based on GPS location or to provide valid key or to provide key for "disabled" such all Graphene chains have (option to prevent block producer missing blocks).
Correct or I'm off here ?
It's quite complicated to bridge Linux, Blockchain, and write another piece of software that will use Geo analysis based on GPS location (International waters or not) and hats down to Notestein for efforts!
Chee®s