Motuz looks like a great product 
Does it use the remote control of rclone to transfer things? If so it occurs to me that you could wrap it up into an alternative web ui for rclone. I don't know if you've investigated the web ui, but it is pluggable - rclone can open a browser for you on some static html/js which depending on the architecture of motuz
I just had a deeper look at the source and it looks like you are using a database and message queue so I don't think that approach would work.
What do you think is missing from the current product? Stuff around user authentication probably!
Nice one! I like hearing stories like this