> For local emergencies the German app solution seems to work adequately

Are you sure about this? While the NINA App did provide me with weather warnings as well as (possibly pinned) warning about the Coronavirus, I have no information about the delay with which those messages were provided to me. It could well have been a delay of over half an hour or more, without me noticing it.

Yesterday I decided to uninstall the NINA App, since it showed me that it doesn't work. It had all the permissions necessary to pop up a message and to notify my with a sound, yet it didn't do anything.