I encourage you to reconsider. While you have the freedom to fork any free
software project, please exercise this freedom responsibly and only after
careful consideration of the downsides such as the opportunity costs of
dispersion and diversion of man-hours and other resources, unnecessary effort
to do what others already have accomplished, etc.
As the FSF says, "If you wish to improve the state of free distros, helping
to develop an existing free distro contributes more than starting a new one."
Debian in particular is such a vast world that I strongly suspect that apps
and other layers of software are already available for it to do what you
seek.
Qubes OS is not on the FSF list of approved distros, but it is GPLv2'd.
