It's more like "who wants to implement it"?
Why an iso?
sudo apt-get install whonix-virtualbox would be cool. (No chance to get that uploaded to packages.debian.org.)
You know what's mess nowadays? Adding a third party (such as the Whonix) apt repository to your Debian system. Awful usability.
apt-add-repository but it modifies
/etc/apt/sources.list rather than adding a file to
/etc/apt/sources.list.d. And the signing key still has to be somehow added. More tinkering. Do you think you could contribute upstream to
apt-add-repository to improve that?
Ultimately, if Debian users could just type "sudo apt-add-repository whonix" and all would be sorted, that would be great! Then it's just "sudo apt-add-repository whonix" followed by
sudo apt-get install whonix-virtualbox and be all set.