I don’t know if grouping disparate projects under the “community” label has any worthwhile benefit. Given the label is meant to classify related operating systems, the label should provide an accurate description of the basis of the system. A simpler solution would be to just say GNU/Linux is a subcategory of Linux (and maybe even sub-sub-categorize by package manager or init system or whatever makes the most sense). Similarly, I think Android and its derivatives are worthy of being its own classification of Linux operating system (as long as you don’t try to claim “it’s not real Linux” or whatever).
With regards to software compatibility, I think it’s rather the other way around - software written for “Linux” usually works on any POSIX operating system, and sometimes even Windows. Unless you’re talking about binary compatibility, which is meaningless in the Linux space anyway.
Nothing ironic about it. There’s nothing mystical about Linux, it’s just a kernel. The guy who made it says he doesn’t care about anything but code.