I use Slack like this for various notifications. I just setup a new Slack instance and created channels for each notification area (smart home, media server, etc). Now all the software in those various areas can send messages (via webhook) and I can set the alert preferences per channel. Makes it easy to quickly look at Slack and know things are running fine.

I also have a #critical channel anything can post to that always has alerts enabled on my phone so I don't miss anything important.

It actually works pretty well and costs nothing.