That’s the thing. I don’t know, my main objective is to just create packages, I am nowhere near knowledgeable enough about Debian’s policies to say one way or another. But by instinct, when I specify a component or group to install to a package, I expect it to install just that one component or group, not everything defined in install().
If you say it is intentional, fine - but on the same page I think that it should be directly documented, maybe as an example or comment.
I was able to get it to create packages during the native build. It took me more time than I would like, but I got there.
I do think that the dh-cmake package should be hinted as a Multi-Arch: foreign, because the mk-build-deps -a<architrecture> has problem installing it when cross-compiling.
Specifically, adding this line. Tested with this package and standard dh-cmake, dh-cmake-compat (= 1), dh-sequence-cpack in debian/control, everything builds fine with dpkg-buildpackage -us -uc -b -a<architecture>.