Just before I tried to install "gnome-software-plugin-snap", I carefully
checked my "/etc/apt/sources.list" file again to make sure that both
"contrib" and "non-free" repositories were disabled.
After installing the Snap package plugin, I restarted the system and then
browsed each category. I didn't see any non-free software immediately. The
listed packages were largely the same, with or without Snap package plugin
installed. This is probably because I only enabled the "main" repository.
Things might be different if I enabled the non-free repositories.
Of course, I cannot verify the license(s) one by one. And I'm rather annoyed
that in the "License" field for each package, only an ambiguous word "Free"
was shown. (Is it free as in freedom or just as in free beer?)
To sum up, I strongly discourage everyone to use Gnome Software. Use the
package manager from Terminal instead, for the sake of freedom.
