RE: is any WCAG criteria to account both default and Dark mode for content

 > One of my continuing concerns is that the large number of consultants
involved with the definition of the guidelines creates a conflict of
interest.

I am quite certain in my mind that that is not the case. Having taken part
myself in many long discussions about draft criteria in WCAG 1.1 and 1.2,
though as a public commentator not a W3C member, and having won many
arguments and lost many others, I know that everyone there involved is
doing the very best they can for disabled people, without any consideration
for potential commercial benefits at all.

Indeed, there would be no need for that. There are enough inaccessible
websites (millions of them, not sure it isn't billions) to keep us all in
permanent employment for centuries to come, so no one has any need for
conflicting interests! And consultants active in day to day consultancy and
audit work at least have the experience needed in this complex field. Much
better than using theoreticians with lots of beliefs but no day to day
practical experience. We don't always agree on how best to tackle a
particular access issue, but everyone does their best to arrive at relevant
and workable solutions. Honestly, I do not think you should have concerns
there!
> WCAG is a product of this well-established hegemony

I certainly do not think that is so. I have never seen any evidence of
commercial interests overpowering others or forcing the way. Quite the
opposite in fact. I, and others like me, have gone in at the public stages
of WCAG releases as independent, one-man bands, and have been able to take
part fully in the deliberations, and been able to influence matters and
achieve improvements, without the slightest suggestion that commercial
giants or even established W3C people might have contrary interests.
Everyone tries to achieve the best possible solution, even if we do
disagree many a time!