I keep a pretty sharp eye on the apple job postings to see what type of people they're hiring. I think they've been working on something similar since about 2014. Around then I noticed they posted for, then hire a lot of optical engineers, (I'd look to find the hire on linkedin a while after the posting was gone) but people with odd skills for apple, contact lenses mostly, lasers, and then a bunch of people who had done PhDs around putting gas/liquid between plastic that can react with projected light.