As for the is-ought problem, if we accept that "ought" is just a matter of calculations in our brain returning an output

But we shouldnt accept that, because we can miscalculate an "ought" or antyhing else. The is-ought problem is the problem of correctly inferring an ought from a tractable amount of "is's".

(and reject that it's a matter of e.g. our brain receiving supernatural instruction from some non-physical soul), then the "ought" is describable in terms of the world-that-is, because every algorithm in our brain is describable in terms of the world-that-is.

It perhaps might be one day given sufficiently advanced brain scanning, but we don't have that now, so we still have an is-ought gap.

It's not a matter of "cramming" an entire world-state into your brain -- any approximation that your brain is making, including any self-identified deficiency in the ability to make a moral evaluation in any particular situation, are also encoded in your brain -- your current brain, not some hypothetical superbrain.

The is-ought problem is epistemic. Being told that I have an epistemically inaccessible black box in my head that calculates oughts still doesn't lead to a situation where oughts can be consciously undestood as correct entailments of is's.