Is there such a guide for the bootstrapping of computation from first principles?
Yes, you could build computers out of relays or vacuum tubes, but their computational power would be very limited. You're not going to be able to run Unix on hardware like that. That technology was very slow and had to be repaired frequently (if you have thousands of vacuum tubes, one would burn out every few hours).
I honestly think though that leaving behind a detailed record of what is possible and how things used to be would be very valuable in this situation though. Just letting people know computers did exist and did require electricity and what electricity was and that we used to burn something called coal to make it would for sure speed up a future civilizations research dramatically.
https://www.opensourceecology.org/gvcs/ http://digitarworld.uw.hu/ttlcpu.html https://monster6502.com/