This super powerful!

I have a suggestion though, this could be syntactic sugar....

we could have namespaced islands like so, using dot notation

@island(name: 'metrics.views-card')
    <div class="metrics-card">
        .....
    </div>
@endisland

@island(name: 'metrics.visitors-card')
    <div class="metrics-card">
        .....
    </div>
@endisland

Outside the islands

<!-- Target all islands -->
<button wire:click="refresh" wire:island="metrics.*">
  Refresh All Metrics
</button>

<!-- Target dedicated islands -->
<button wire:click="refresh" wire:island="metrics.views-card">
  Refresh views-card
</button>

<button wire:click="refresh" wire:island="metrics.visitors-card">
  Refresh visitors-card
</button>

Named Islands