To be frank, many of the GNU extensions are very useful. BSD tools have their own extensions over POSIX as well. Anyway, GNU software is FOSS and tends to be portable and so you can create something like GNU/FreeBSD or GNU/OpenBSD or whatever (Debian did it in the past). Naturally, the GPL/LGPL/etc. may not be "free" enough for the tastes of the BSD devs, but this is getting into politics.
I tried using meson for https://github.com/shlomif/mini-factor , and while it worked fine locally it turned out to require python 3.6 which made it hard to install on Travis-CI. I ended up created a complementary cmake build system.
I like LiveJournal.com or similar's commenting engine the best - it has previews, it supports HTML with opening and closing tags, etc. The WordPress.org blog commenting system is absolute braindamage and it is one of the reason why I don't use WordPress.