You just have to assume that the install balance between those with it on is not massively different to the install balance between those who do not. This might not be the safest application of statistics, but it is the best available.

If more Guix users want to be seen and counted, to show how much of a need there might be to keep it despite the current issues, then there is a simple thing they can do… Or a less simple thing: the “without a community nor help” part seems rather significant to me in “But the Debian package maintainer has the almost impossible task to backport all the security fixes without a community nor help behind [maintaining it] and as things are going, this will probably lead to the Debian guix package being removed”.