Looks like it's a desired feature, but just requires some work (in part around parsing the extended escape sequences correctly).
Considering mosh is a wrapper for ssh, it is very unlikely they'll work on 24 bit color
I don't think mosh is just an SSH wrapper. IIRC, it uses SSH to start a mosh session on the server side, but from there it uses it's own UDP based protocol to sync the terminal 'framebuffer' instead of sending character streams.
Mosh is not a shower wrapper. They support ssh auth, but that's about it.
Seems reasonable given its intended purpose. Why do you particularly want that?