The safest way to test an Allwinner H6 custom ROM is via microSD card—do not overwrite the internal eMMC until you are confident.
Several developers on the Freaktab and 4PDA forums have ported AOSP and Leanback ROMs for H6 boxes. allwinner h6 custom rom
Yes, but with caveats.
For those using their H6 box purely as a media player, these are excellent. The safest way to test an Allwinner H6
cd u-boot
make orangepi_3_defconfig # or tanix_tx6_defconfig, pine_h64_defconfig
make CROSS_COMPILE=aarch64-linux-gnu- -j$(nproc)
Output files: u-boot-sunxi-with-spl.bin (for SD card / FEL) Output files: u-boot-sunxi-with-spl