macOS pleasantly has a few on-demand wake-up-from-sleep features, most notably that a wireless keyboard or mouse/trackpad will wake up a Mac attached through Bluetooth.
The music scenario is less user-friendly, it appears.
You can configure a Mac to share its music collection.
But if you let the Mac containing your music collection go to sleep when unused, then iTunes on another Mac on the same local network will not see the sleeping Mac's music, and there is no way to wake up the Mac with the music collection from sleep—short of walking over to that Mac and waking it up.
I would like to confirm that this is as good as it can get. And yet a Mac can be woken up through ssh, so it's not a stretch to ask about WiFi.
Is there a way to configure iTunes on a Mac to wake up another Mac to access the music collection on it? Is there a way to share the music collection through Bluetooth to achieve the same, perhaps by forgoing video sharing since the bandwidth may exceed Bluetooth's?