Please don't bring Musk into this. We don't need another overhyped vapourware product that might or might not work if it actually is delivered.
There are already shark deterrent devices on the market and if you are a Western Australian resident the state government will give you $200 rebate. In addition if you live in Australia most areas are covered by a shark monitoring system.
No shark deterrent will work 100% because hunting behaviour of sharks varies greatly between species. Even within a species they adapt their hunting behaviour to environmental conditions.
I think a better approach would be to combine deterrent devices with monitoring and environmental details (migration pattern, ocean water temperatures, fishing boat activity etc) in a warning system.