On a mildly related notes:
The purely HW-specific bits (CPU, RAM, etc.) are in the NTX HWConfig tag found in a clump of bytes at the start of the block device.
You can decode the data on your own device via ntx_hwconfig, or you can
implement the bits you need
yourself to avoid calling that thing (it appears to be statically linked against the glibc, brr!).
Various generations of Kobo kernels source packages have more or less detailed info in the related header. Earlier kernels were messy, but a bit more verbose.