Spoiler:
* Polished with a Magic Eraser then with toothpaste and water.
* Waxed with Mother's Carnauba Cleaner Wax. I had an old bottle lying around.
All done by hand. Took around 15 minutes.
A couple folks on r/mk have tried using acetone vapor, which can yield even better results. However, if you use acetone vapor too long, your keys will melt. And "how long" isn't an exact science.
Opinions?