Critical push notifications

See @Dijker ‘s post above: some alarms also trigger the critical alerts automatically (without a flow).

The word “Critical” implies “should work at all times”, which is probably not the case with Homey.

I wonder: because Push notifications can get rate limited, both by Homey and Android:
Are Critical push notifications built as a separate “service”?
Or does it just go down along with activated rate limits from the regular push notifications service?