Hey Ryan!
First of all, this all sounds very promising. In my humble opinion you are vastly underplaying your own skill in terms of design, but that's also why we can trust that you'll recognize amazing design once you see it. Looking forward to seeing what the team working on the design has cooked up 😉
Now, please forgive me for jumping directly into asking for stuff, but...
I know this is small thing, but it would be quite nice if the new admin made use of CSS variables wherever it makes sense; colors, font sizing, etc. (Or provided them as an alternative for non-core tools to use, in case it is not feasible to use them for actual admin styling.)
The reason I'm saying this is that I've built various admin tools that I wanted to look like the admin theme, and since there is (to my knowledge) currently no simple way to access existing colors etc. in CSS, any non-Uikit elements I've had to "hard-code" to use current styles. This includes the default green/cyan/blue color theme, current spacing and font size practices, etc. As a result said custom elements may look out of place once the theme is updated 🙂
(Just for the record: SCSS/LESS might be an option, but that feels like a lot of unnecessary overhead and complexity where vanilla CSS would easily suffice. I'd really like to avoid that if possible, and to me it seems like CSS variables are an easy and well supported alternative.)
Additionally: it would be awesome if accessibility was a consideration while creating this new admin theme. I know it has been considered to a point in the past, but has never been a major goal. Hopefully we can push things forward in this regard in the future. If there's something I can help, I'd be happy to 🙏