So looks like RG have released this little device it is a RS90 in a RG300 shell which is a good thing because opendingux has been ported to the device i have tested it myself and confirmed working. If you would like instructions how to flash the device i will post them below.
CPU Ingenic JZ4725B 360MHz RAM 32MB Storage 256GB Screen 2.8" 320x480 Slot MicroSD Gamepad DPad, 4 Buttons, M1, M2, Start, Select, L, R USB Client Battery 3.7V 1800mA Dimension 119mm x 82mm x 25mm Weight 325g Others Vibrator
Please note you need the correct drivers for windows 10 installed first follow this https://boards.dingoonity.org/retrominirs-90/a-quick-guide-to-flashing-opendingux-on-the-rs-90-using-windows-10-x64/ guide first to get them installed then continue below.
Step1 Linux 1. download flasher.tar.gz from release page here https://github.com/steward-fu/rg99/releases put RG99 into boot mode (Press START and then power up) plug USB into PC command: $ sudo flash.sh
Windows 10 1. download flasher.tar.gz from release page here https://github.com/steward-fu/rg99/releases
2. extract flasher.tar.gx
3. plug USB into PC
4. put RG99 into boot mode (Press START and then power up)
5. run the flash.bat
Step 2 flash .img into sdcard (this is file system) download v1.0_sdcard.img.7z from release page here https://github.com/steward-fu/rg99/releases prepare 4GB or larger MicroSD flash sdcard.img into MicroSD
Thanks goes to the hard work of the devs Pcercuei & Steward