LDK Series

The LDK or Little Dragon King line of devices use similar hardware to the RS-97s, but are made by a different company rather than Anbernic. They come in both landscape and portrait form factors, and include an easily accessible "internal" SD card underneath the battery. Interestingly, the landscape form factor came out after the portrait one, but uses an older processor (JZ4760, the landscape uses the newer JS4760B version).

AliExpress link for portrait
AliExpress link for landscape

Specs:
Screen: 2.6 inch 4:3 (Portrait) 320x240
2.7 inch 4:3 (Landscape) 320x240
CPU: JZ4760(B) MIPS
RAM: 128M DDR2
Internal SD: 16GB

RetroFW Download:
LDK Portrait
LDK Landscape