Disclaimer: I have no idea what I'm doing. I found this in a trash can and I'm trying to make it work. Shit isn't even in a language I understand. And I'm too scared to plug it on my computer. Also I'm poor, I can't get the "Atmel ICE Debugger" (if that's even the correct port on the board ??). Send help.
Here's what I found about (TL;DR)
CPU is a (epoxy blob) SNC7001A. It's a 16-bit fixed-point DSP. Putting it backward on the rom took me 2 hours to figure out. Thanks, whoever got this wonderful idea. Datasheet : https://www.sonix.com.tw/article-en-1209-6271 Most is undocumented/private about the s9ke, I found some s8ke and used that to build upon. Most may be outdated or wrong. Send help.
ROM is saved inside a "25Q80CSJG" GigaDevice Semiconductor SPI flash chip. Datasheet : https://www.alldatasheet.com/datasheet-pdf/pdf/1135820/GIGADEVICE/GD25Q80CSJG.html
Screen is TS24TP screen (320x240), seems to be RGB888.
There is a TP4056E Battery Charger IC with labels 4056E XLS1D1P
There also is a 4871 80109 chip.
FU and FA are the file downloaded from the website when trying to "upgrade" an 1.0.0 device to 1.2.0.
The only diff between FA and FU is the first 4 bytes : 45 FE 64 A7 which translates to JMP 0x45A764 in S9KE assembly, that seems to match the SPI_FLASH address space...
They contains LAME3.100 encoded MP3s and "BM" encoded BMPs. Find where they are : python SNC7001A_disasm2.py FA.BIN --map