This is exactly the comprehensive reply I was hoping for, thanks. I dug up a Carroll post on the arrow of time and the big bang for this thread which turned out to be from 2004, so I know the feeling.

If there are any other non-experts like me this far down this reply chain who are interested in dark sector speculation, in addition to raattgift's excellent links I'd recommend the Wikipedia page on the Lightest Supersymmetric Particle [1] and Rob Reid's recent podcast with dark matter researcher Priya Natarajan [2].

[1] https://en.wikipedia.org/wiki/Lightest_supersymmetric_partic... [2] https://after-on.com/episodes-31-60/036