The article you link is to the Debian wiki, which as I suspected suggests the
BBB/Debian combo is as free as Debian. Debian falls just short of FSF because
of the availability of non-free repos and documentation that suggests
non-free software. Provided you do not use these Debian + BBB is reasonably
free. It will just never be certified by the FSF. Orange pi is not directly
recommended in the same fashion by Debian, the only way to know is to install
a vanilla ISO, and see if it works.
I doubt anyone has personal experience that will result in them being able to
tell you definitively, most libre folks are pretty leery of ARM in a general
sense.
A possible resource would be the Replicant community since ARM is their bread
and butter.
