Hi, I hope you are doing well.
You want a Messenger that looks like an app you sent with a matrix SDK. Working with this SDK is a completely new experience for us and because this SDK is written in java and for connecting to the Server we should use HTTP API, We really like to do this project. We are very good working with java and API,
Also, we will support the app and fix bugs for 6 months so don't be worry about future bugs.
Hope to hear from you soon.
Thanks