Thank you all for the feedback! I needed to gauge demand for the feature before the product team would consider it. The nature of Seller Central makes the implementation of Dark Mode difficult. There’s no single monolithic app “owner” - rather each individual product is owned and maintained by an individual team, and updated and released on their own schedules. (You can contrast this with the Seller Mobile App, which has a single owner, and gets built, released, and distributed as a single app through the app store.)
With regards to adding the feature to the Forums, I can confirm that I’ve been able to get it on the roadmap for Q1 2023.
This is not the case. Our product team does not have this on their roadmap at this point. I’m currently drafting a proposal which will include inputs from this thread with a goal of presenting to them in the next week. Stay tuned.