Siren as a notifier?

I might have a meh moment, but I cannot see how to use a siren as a notifier in, e.g. an alert. That seem quite a normal usage of a siren to me.

Do I miss something obvious?

Not 100% certain what you mean. It is not a notifier - you just write an action to switch the siren on/off. I presume you see the siren as a device and can switch it on, and that the switch has an entity associated with it? What siren is it?

What I mean is that I would like the siren to trigger as the direct result of an alert, via notifiers:.

It seems obvious to me it should be possible, but I might be wrong and I should go through an automation, but that would seem like an oversight…

There is no “template notifier” either, unfortunately…