but user adoption is abysmal comparatively

I guess this is a matter of perspective. What I was saying in my previous comment is that what people commonly refer to as “Linux” (as in “Linux distributions”) is not just Linux (which is just a kernel) but also includes a bunch of other stuff, including GNU (that is what GNU/Linux refers to). If you’re talking about the actual thing called Linux, you’d be right, because most GNU systems are GNU/Linux systems, whereas arguably most Linux systems are not GNU systems; Alpine and Android are non-GNU Linux systems.

However, if like many in the Linux fandom you discount Android, then most Linux systems are GNU systems and vice-versa.