As we are mainly responsible for general issue of Microsoft Teams, your question is more related to development which is not in our scope. I would add office-teams-app-dev tag for you.
Meanwhile, this article can provide some benefits for your idea.
You could create a deep link to a chat as below and open it in browser. Just replace the content of users and message.
https://teams.microsoft.com/l/chat/0/0?users=user01[@](/users/na/?userId=a28c79c1-c609-48db-b55f-1783d1187afb).com&message=This is a message.
Then, it will open the conversation with user01 and input the message automatically.
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