The project is already very mature, around 5 years of continous development, and is probably approaching the maximum that can be achieved with the hardware in these radios.
The GD77 type radios, including the DM1801 V1 and RD5R and MD760 etc have virtually no free program memory (ROM) to add any major new funcationality.
The UV380 / MD9600 radios have more ROM capacity, but the UV380/390/DM1701 all have the same cheap RF chip ($1), and lack of internal hardware connectivity as the GD77, so again, its unlikely that much more functionality could be added.