Have a look at the MixedRealityToolkit from Microsoft. I'm learning this and Unity because I saw a very different future when I put the Hololens 2 on the first time.
Hololens is already out and has some good developer resources. Apple is supposed to have something in the pipeline for release sometime in the next couple years (could just be a rumor). If that happens, I think that would be the catalyst for mainstream adoption. I wouldn't be too surprised if google redesigns and rereleases Glass to compete too.
I don't think Apple Glass will have that when it comes out, re: privacy. The parents lack cameras, but may have some form of lidar? Maybe depends on the one you look at?
I'm surprised they aren't used more extensively in industrial companies. They would be great for training. Citi Bank has a video on YouTube that demos their vision of use for financial companies too.