Thank you all for your suggestions! I started off playing with app-queue-toggle-context-custom, but as far as I could tell it was completely ignored. I then played with making my own feature code in extensions_custom that duplicated the auto-generated ones, but with a different feature code.
But actually, as I thought about it, there are some other events that I will also want notifications on Microsoft Teams, so I ended up working with the AMI monitoring. I used lgaetz’s code as a base, then switched to the following library to handle parsing out the AMI events: https://github.com/marcelog/PAMI
It’s still pretty rough, but it looks like I’m on the right track.