From what I know, there is no direct way to inject messages to a teams chat - no matter if Meraki or any other vendor should be your trigger. Iirc There is also no connector in Flow aka PowerAutomate to post a message in a chat - only to a channel.
What we do in our case is using webhooks as triggers in Flow to post messages to channels and @mentioning important people to fix stuff so that they will get a push notification in Teams. Good thing about it is, that we can communicate and document what we did to fix issues with the comment function in the generated thread in the channel.
Many people don't trust Flow, but it has turned out as a reliable solution for months in our case.
And just to be complete: You're able to generate links that WILL post a message to a teams chat if you click on them on a PC that has valid Teams session open. But that won't help you until you create some kind of dirty scripting stuff 😁
https://teams.microsoft.com/l/chat/0/0?users=<user1>,<user2>,...&topicName=<chat name>&message=<precanned text>
From: https://docs.microsoft.com/de-de/microsoftteams/platform/concepts/build-and-test/deep-links