I’ve browsed the github issue. I’m not sure the source packages is the way to go (it’s a bit of an rpm-ism) since it’s all built from the github sources. The
uname -a command includes the github revision for building the kernel. Do a checkout to that revision from a clone (or do a download from the github at that revision) and there you are.
If you are building third-party kernel modules, you should try to set them up as a port, then it should just get picked up with all the other ports when they are rebuilt for a release and pkg will do the rest. Developing a kernel module not ready for general consumption? Well, if you doing it against -CURRENT (or TrueOS UNSTABLE), you are going to be following the source. (My assumption, since FreeBSD’s ABI doesn’t change in -RELEASE/-STABLE, but does change often in -CURRENT).
Could the repositories on github have tags to make this a bit simpler to follow (especially for the ports tree)? I believe it could. The good part is that—aside from using the github repos—the directions for building kernels and ports yourself follow the FreeBSD handbook and do work (from personal experience).