GNU and BSD are different projects with different heritage, despite sharing common roots on Unix
I suppose one could argue that Alpine is not GNU in the same sense that GNU's Not Unix: Alpine set out, sort of in a crazy villain mad pursuit, to replace GNU components in GNU/Linux just like GNU set out to replace Unix components in Unix. while GNU made far-better-than-Unix components while at that, Alpine selected inferior ones, but nevertheless Alpine accomplished its mission of getting to a GNU-free system. it's hardly distinguishable from GNU/Linux in heritage and appearance, all the way from Alpine to GNU/Linux to Unix. so I conclude that Alpine managed to put together a GNU-free GNU/Linux Unix-y system. which is quite ironic, if they set out to rid themselves of GNU in their primary qualifier :-)