Has this feature been coded in UT?
Emergency Broadcast messages support has not been integrated into UT as of yet. Indeed, I know of no other non-Android Linux OSes or shells that have them yet either.
However, ofono does have some API for them, so it should be possible to do the work for them in UT. It just needs someone to spend the time to do all the work. I don't know if ModemManager has any support for them at all though, so implementing them for other shells may be even more work.