I was wondering whether the Guide pointed to the actual doco. The Guide is not perfect. I had not yet checked. (NetBSD has a Guide; FreeBSD has a Handbook; OpenBSD has a FAQ. One of the reasons for keeping the names straight is that there is something else called by its authors the OpenBSD Handbook, which is not produced by the OpenBSD people, and is a perennial thorn in their sides when people come to them with "I read in your Handbook that …" problems.)

Reading that chapter, it turns out that it does. Maybe it should stress the point more, but the actual doco is the likes of these:

* https://cdn.netbsd.org/pub/NetBSD/NetBSD-11.0/evbarm-aarch64...

* https://cdn.netbsd.org/pub/NetBSD/NetBSD-11.0/i386/INSTALL.h...

* https://cdn.netbsd.org/pub/NetBSD/NetBSD-11.0/amd64/INSTALL....

* https://cdn.netbsd.org/pub/NetBSD/NetBSD-11.0/amiga/INSTALL....

* https://cdn.netbsd.org/pub/NetBSD/NetBSD-11.0/sparc64/INSTAL...

… and so forth. Plus the manual pages for postinstall(8) and the like.