In the past NuttX used to have a Buildroot that was able to generate the toolchain, etc. It is still around, some time ago David Alessio fixed it.
It generates more than that. It generates most of the tools that you need including kconfig-frontends, genromfs, etc. And it is easily extended to include more host tools. It is 90% of an SDK, depending on how you define an SDK.
It can never be a part of the Apache NuttX project, however, since most of the tools are GPL. If someone wants to take over the build root and expand on it, we can do that.
