HomeKit and sensor notifications: What's supported, and what's not?

I have the same question as this: “Homekit notify when temperature sensor above/below threshold?” from @styledatom

I'd like HomeKit to send me a notification when my temperature sensor exceeds a certain threshold, or drops below a certain threshold. My understanding is:

• triggering a push notification from a temp or humidity sensor is not currently supported
• the workaround is to use a third-party bridge (something like HomeBridge / HOOBS) that can make a call to an external push notification service (this workaround requires additional hardware and tech nerdery!)

My question is:

• How can I find out what devices/conditions can trigger HomeKit notifications, and what can't? I.e., what's supported and what's not?

I see lots of posts here and on Reddit of people (like me), frustrated because when a notification isn't supported for a particular device or sensor, the "notify" option simply doesn't appear.

(This is extra frustrating because, for these sensors, automations are supported, just not notifications. For example, if my temperature sensor gets too hot, HomeKit can take that trigger and turn a smart lamp red. But it cannot also send me a notification. 🤔)

Is there just a posted list somewhere, like of the HomeKit spec, listing what it can and can't do, in this respect?

Thanks!