However looking at the processor in the radio and also the EEPROM size; what can be done with this radio is relatively limited
The CPU / MCU processor appears to be a Chinese clone of the STM32G030x8
This is a quite low spec device. Only 64k of program memort space, compared with 512k on the GD77 and 1024k on the UV-380/DM-1701/MD-9600.
It also only has 8k RAM. Whereas the GD77 has I think 128k and I think the UV-380/DM-1701/MD-9600 have something like 192k (its not all completely accessible by the processor)
This radio also only had a 64k EEPROM and no other memory. Compare that to the GD-77 additional has 1Mb of Flash memory and the UV-380/DM-1701/MD-9600 have 16Mb
The processor is also not fast. I think its 48Mhz instead of the 168Mhz processor in the UV-380/DM-1701/MD-9600.
I think you get the picture.
The existing 'hacks' are basically single additional patches that can only be applied one at a time to the official firmware.
i.e There probably isn't space to support the RSSI bar graph, and the specrum analyser and the Pong game all at the same time, otherwise I suspect the author would have at least bundled the RSSI functions in the same package or the RSSI stuff and the spectrum analyser
What the developer has done is basically intercepted the System Timer Interrupt, and either runs his code or the official code, or his code then the official code.
What the devloper has done is technically clever, but ultimately fairly limited.
Before the OpenGD77 development started, I worked on doing something similar with the GD77 to allow direct TalkGroup entry and improving the DMR ID database functionality. But ultimately I realised this was not a good approach, becuase patching the official firmware gets progressively more difficult as you try to add more functionality, and you very quickly run out of program space.
What is quite interesting in this radio is its RF chip, as it operates over a very wide frequency range.
However, the available documentation appears to be incomplete, becuase the official firmware seems to be able to receive AM, but the data sheet for the RF chip makes no mention of AM or even mode selection.
I've been told by people who own this radio that the AM reception is not at all clear. So possibly the RF chip is actually FM only and the official firmware is doing some trick to receive AM.
Or possibly the RF chip can be sent additional microcode by the CPU to add functionality. This would be the same as the SI4735 radio chip, where Tecsan radios using this chip, sent it secret microcode to allow the chip to support SSB Rx even though this is not in its data sheet
The hackers intercepted this microcode and used it in various Arduino based receivers.
So potentially the RF chip in this radio has some undocumented features.
But as no one seems to have done a teaddown to the point of looking at the data traffic between the MCU and the RF chip, ... ADFIK no one knows how to actually set the RF chip into AM mode.
Edit 1
The RF chip used in this radio is completely different from the RF chip in the GD77/DM1701/UV380 and to the RF section in the MD9600
So it would not be possible to take any hacks for this radio and use them on any of the OpenGD77 supported radios.
Edit 2
The RF chip is a BK4819
The data sheet has this text
So according to the data sheet its FM only, but includes some FSKThe BK4819 is a half duplex TDD FM transceiver operating within 18 MHz ~ 660, MHz, 840 MHz ~1300 MHz band range
Besides speech communication, the BK4819 on-chip FSK data modem supports F2D and F1W emission to be used in both FRS and DPMR band for text message and GPS information exchange