@Nitin S It's a good idea to build Bot and send notifications for your scenario. You can use Proactive message to send message.
Also please note that in order to send message, your Bot needs to be installed for each user (since application permissions are not yet there).
You can install the app in personal scope. You can use Subscriptions for /chats/allMessages -- all chat messages in organization and then notify user in 1:1 using bot.
Unfortunately at the moment, you cannot use Microsoft graph for this. Being said that, please file user voice for your scenario so that it could be considered for future implementations.
Please upvote if this helps. Thanks!