SDF used NetBSD. In the 90's they switched for a while for RH under X86. Worst era ever, very insecure. Now they use NetBSD X86-64.

On Hyperbola GNU/Linux, they will shift into OpenBSD, they got fed up with the corporate slopware (and propietary Linux became). They will still make Hyperbola BSD GNU-license compatible, from core to the userland tools.

In my case, I wish Emacs and GNU developers embraced plotutils and left out Gnuplot (is not GNU at all; worse, it conflicts with the GPL) and made Texinfo independent of LaTeX to produce PDF and HTML files with equations. Groff + troff+pic+eqn already do that, no Texlive needed. So can mandoc under OpenBSD, no magic needed, everything under few MB's.

Texlive it's huge (full instal it's over 7GB) and the so-called free FSDG is not 100% free, at all. With just that GNU Emacs would be truely GNU-standalone, relying on GNU tools for plots under Emacs' Calc and Texinfo books exported into PDF. A good plus for security.

Once you get that working, the rest would just follow their way. Also, GNU Hurd being developed with propietary LLM's/SAAS it's a disgrace against what GNU stands for too. They can go back to the right path, but they need will, for sure.