Buildroot Image

[sawdust]

Buildroot & Debian Image

I managed to create a buildroot image with kernel 5.10rc4 for the pinecube.

How do you merge/blend Buildroot and Debian? 
Seems like you are under-utilizing Buildroot, and could just as easily build U-Boot and the kernel separately? 
BTW rc5 was released this week.  I've started a build for Pinecube as I'm writing this.

Unfortunately Wifi is not working yet.

Because there is no driver in that kernel for the radio. 
The driver for the RTL8189ES is not in mainline.

Also media-ctl brings an error "no /dev/media0"

That means that there is no image sensor (camera) device. 
If you've built the kernel with sunxi_defconfig, then there is no image sensor enabled in that configuration. 
You need to enable (using `make linux-menuconfig`): 

  Device Drivers -> Multimedia support -> Media ancillary drivers -> Camera sensor devices -> OmniVision OV5640 sensor support

Regards