Send a chatmessage from an app to a user using GraphApi

I have a software application that needs to send automated notification messages to individual users in Teams.

It's the first time I'm using the GraphAPI. An app was created for me in Azure with a client id and secret. The authentication is working fine (as application, not a delegated scenario).

I'm trying to figure out which endpoints I need to call to send the chatmessage but facing some missing links. In reverse order:

• Send chat message: requires a chat-id
• Get chat between user and teamsApp: requires an app-installation-id
  • So appearently The user needs to install the app first? But this can also be done through API
• Install an app for user: requires an app-id
  • I have no idea where to find this id

Am I going in the right direction with this? Do I need to go for a deligated flow? Should I be using a bot? Any pointers are very much welcome as the documentation is lacking in higher level concepts and structures. Thank you

We ran into a dead-end with GraphAPI:

• Application permissions is not supported for sending chats

• Delegated authorization requires the user to go through a confirmation page each time they log in. This wouldn't work for my case since I'm trying to send a chat from an application, it has to be pure API, no user interaction.

We ended up using PowerAutomate to expose a webservice that can send chat message directly to users.