He makes something called the color hug, which is a device that does a spectrograph.
Displays are now very different to each other. Mobile phones show advertising really well, but are crap with your photos.
Other devices are either closed source or unsuitable for displays.
The color hug plus is the third version. It will illuminate stuff, so you can measure paper.
This is a hobby for him.
The hardware and software are both open source.