Problem
We have a notifications service that systems can connect to, to send notifications.
We want to deliver notifications to users in our organisation via teams, without them having to install anything (such as Web Hooks, Bots etc).
Ideally the notifications user will popup and start talking to the user when they are sent a notification.
Question
How do I achieve this? MS Graph API?
I have tried application permissions, and sending messages on behalf of other users is blocked by the API.
I have tried delegated access (with the end user being a service account), although this fails with 2FA - a service account can't manage 2FA flow!
I have tried a bot, but users need to install this.
I have tried web hooks, but again, users need to install this.
How can I send one-to-one Teams Messages?