OpenBSD checks a number of boxes;
- I have CDROMs that date way back
- It has tools that cover all the basics so that starting from the beginning might not be necessary
- supports a number of CPUs
- generally speaking it's reliable, sensible, and inline with *nix thinking
The thing is... if I had to everything is right there in the box, so to speak.
- packet filter for building your own firewall
- haproxy as a reverse proxy
- nginx, lighttpd, apache web server
- maria, mysql, postgres, sqlight database servers
- asterisk phone server
- certbot, letsencrypt, openssl crypto
- firefox, mozilla,
- freeradius authentication
- chroot, jail
- scripting languages like bash, perl, python, tcl, lua
- OpenSMTPd, postfix, mutt, post - email servers and client
- code editors like vim, joe, jed
- git and fossil version control
- and with all of the source packaged here you can make world.
What I'm saying here is that everything you need is here. If you put the whole thing on a USB and moved to the north pole you could still get great work done without the distractions from the modern world that just adds complexity and risk.