Android on Rock64 SD Problem

[tllim]

Hi, first of all, i wanna say that i'm quite happy with the Rock64, i've a 4GB, Rev 2 version, that is working like a LibreELEC Media Center 24/7, PulseAudio Server without (almost) a glitch.
I'm trying to install Android on a SD Card, so far i've tried on a number of Cards without success;

8GB Kingston Class 10
16GB Sandisk Ultra
32GB Sandisk Extreme (i own a Couple)

The images were the following; 

android-7.1-rock-64-rock64_atv-v0.3.13-r115-raw.img
rock64_20171204_stock_android_7.1.2_rooted_sdboot.img
rock64_20180623_stock_android_8.1_sdboot.img
ROCK64_20190621_stock_rooted_android_9.0_sdboot.img
ROCK64_dd_20190621_stock_rooted_android_9.0_sdboot-16GB.img

ROCK64_dd_20190621_stock_rooted_android_9.0_sdboot-32GB.img

Flashed in a number of ways, first the Pine64 Installer, then Etcher, the Rockchip SDTool, Win32DiskImager, DD on Linux. 
None of the combinations booted into Android. 

I know that this is a developer SBC, i also tried Armbian and Manjaro ARM flawlessly, so i find quite strange this behaviour.

The PSU is a 3A 5v, i can acccept that maybe this unit will never boot into Android, but if there is a tip, i'll take it. 
i don't own a eMMC memory, i'm from Argentina and they are quite difficult to get here. 

Thanks!

For non-DD firmware build, please use RK tool to program.