IIRC, once you built and installed the Pi image, in order to update you needed to reinstall it all locally, as NixOS doesn't consider ARM built on x86 to be identical to ARM built on ARM. However, I believe they now have an ARM build server that generates both precompiled ARM-from-ARM images and packages.
IIRC, once you built and installed the Pi image, in order to update you needed to reinstall it all locally, as NixOS doesn't consider ARM built on x86 to be identical to ARM built on ARM. However, I believe they now have an ARM build server that generates both precompiled ARM-from-ARM images and packages.