I'm just after C headers and Makefile like the NRF5 SDK.
All I found was some "AppImage" file for x86_64 which I've no idea what to do with - I tried unzipping it, but it just seemed to contain a few executables rather than the SDK.
I'm quite confused why it's so difficult to find a link for the SDK for this device, it's noted in multiple places across nordicsemi.com that it has an ARM core and we can program it, but I can't find any mention of where to grab a starting point for this.