I think that early image does not have the magical devicetree swapping for the eMMC/sdcard device and so the boot entries for the rootfs point to the wrong thing (would need manual fixing of boot.cmd and fstab), the latest image from Ayufan should work like for the Pinebook, e.g. boot from sdcard, then use the script in /usr/local/sbin to write the eMMC...
https://github.com/ayufan-pine64/linux-build/releases
https://github.com/ayufan-pine64/linux-build/releases
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