Thanks for working on Pantheon packaging! I couldn’t do all of that without you.
I’m currently working on making the KDE variant official. I think it’s definitely possible to create an official Pantheon variant but it will need people to maintain it (i.e. I will not commit to do that). I will probably keep building other desktop variants once the KDE one becomes an official one but support will be minimal.
See also the work from @walters in pre-RFC: Rebasing Silverblue on CoreOS that should make it easier to build and maintain more variants.