There are a couple of issues with the linux-nvgpu package hash:
The package filenames have underscores instead of hyphens and this leads to buildroot not being able to find the .hash file. This generates a warning but the build continues.
On the feat/jetson-nano-support-latest branch fixing the filenames then results in a build error because the hash value is incorrect.
There are a couple of issues with the linux-nvgpu package hash: