I'm a bit loathe to mention this, but it should be pointed out that GG&S has a really bad reputation among many academics as fatally flawed analysis [1,2,3,4,5,6]. It makes all sorts of methodological, factual, and theoretical errors that undermine the entire argument.

But rather than make anyone go through the rather verbose things I linked, a simple example demonstrates the point: The core of Diamond's argument is that geographical factors determined the course of world affairs between approx. 1600-1900. Not the hundreds of millennia before, nor at any point in the future, only those 300 years. That's a weird argument to make about factors that have essentially always existed and presumably always applied. Even if we accept everything uncritically, the result is a pretty terrible "grand theory" that can only justify things post-hoc.

[1] https://www.livinganthropologically.com/eric-wolf-europe-peo...

[2] https://louisproyect.org/2009/04/24/jim-blaut-on-jared-diamo...

[3] https://www.jstor.org/stable/3054276

[4] https://www.insidehighered.com/news/2005/08/03/guns-germs-an...

[5] https://www.reddit.com/r/badhistory/comments/2vf565/myths_of... <--- Despite being reddit, it's actually credible and a good introduction to Restall's 7 myths

[6] https://doi.org/10.1080/10455752.2013.846490 <--- Despite being a published article, this infamous paper's commentary is on the same informal level as most of these.