How do I publish the work of my elderly father, a "fringe" scientist? I am trying to figure out the best way to publish my elderly father's life work. He says he would be considered a &quot;fringe&quot; scientist or an independent researcher. Should we self-publish? The subject matter would be of great interest to those interested in earth-moon systems, and the Egyptian Pyramids. How should we proceed?
There are precedents for this.
J.S. Bach assumed that his music would be forgotten after he died. It would have been it if weren't for the efforts of Mendelsohn, Schuman and others. Nowadays Bach is considered by many to be the greatest composer whoever lived. His work is to be heard ubiquitously.

For about 50 years after Bach’s death, his music was neglected. This
was only natural; in the days of Haydn and Mozart, no one could be
expected to take much interest in a composer who had been considered
old-fashioned even in his lifetime.
https://www.britannica.com/biography/Johann-Sebastian-Bach/Reputation-and-influence

With regard to publication by children of a parent's work, there is the case of Pierre Fermat.
Fermat was a great mathematician by any measure. However his widespread recognition by the general public was the result of his so-called Last Theorem. This came to light purely as a result of his son reproducing a note from Pierre's handwritten note in a margin.

Written in 1637, it wasn’t actually his last theorem, but nobody knew
about it until his son found it five years after Fermat died. Years
later, after all of Fermat’s other theorems had surrendered to
mathematical proof, this remarkable theorem resisted all assaults.
https://www.famousscientists.org/pierre-de-fermat/


Self-publishing is always an option even if it ends up being simply a treasured family keepsake.
Without knowing the details (Did he visit and excavate the pyramids? Did he decipher hieroglyphics that no-one else could?) it is difficult for us to answer.
I think you need to consult an expert in the field. Alternatively you need to get a publishing agent in the field of interest. They will negotiate the traps and tricks of the publishing industry for you (at a fee of course).