I recently bought this device because it was the only small board with eMMC and onboard ethernet. Love the hardware, but the BSP support is horrible. They use an ancient U-Boot 2017.09 version, which doesn’t support extlinux. There are 8 (wtf?) different partitions created and their official Alpine image uses an immutable rootfs overlayed with a data partition, so you can’t even run docker on this thing 
The kernel is dumpeed onto the disk and doesn’t seem easily upgradable unless you overwrite it with dd 
I saw DietPi is the only distro that supports this board. I just flashed the image and examined it. It uses the same weird 8 partitions. I saw that there are some u-boot-current and u-boot-edge packages, which (so I hope) are not this vendor crap.
linux-u-boot-nanopi-zero2-current.deb 2026-03-12 12:10 487K
linux-u-boot-nanopi-zero2-edge.deb 2026-03-12 12:02 487K
linux-u-boot-nanopi-zero2-vendor.deb 2026-03-12 12:00 487K
Did you succeed in building an up-to-date U-Boot image that works with extlinux? I also tried upgrading the kernel and the DietPi wouldn’t boot anymore. What’s the right way of having something newer than the vendor 6.1 kernel?