Again, that’s specific to it being proprietary software. I’ve got some devices in my home that are connected to the local network (but not the internet), and have configured Home Assistant (which I’ve got running on an old desktop PC) to send a notification to my phone when it detects that those devices report that they’re finished with what they do. That’ll keep working until I turn off the Home Assistant server or replace the devices.
It won’t work forever. It’ll stop working once they stop supporting the app or shut off the servers.
Again, that’s specific to it being proprietary software. I’ve got some devices in my home that are connected to the local network (but not the internet), and have configured Home Assistant (which I’ve got running on an old desktop PC) to send a notification to my phone when it detects that those devices report that they’re finished with what they do. That’ll keep working until I turn off the Home Assistant server or replace the devices.