I have no idea on the limitations of this spectrometer (perhaps with some filters/adapters) nor did I spend time searching for what is already out there but what could be interesting is:
Jewelry (or money) authenticity as in: Is this real (24/18 karat) gold, diamond etc
Drug/poison/bacteria detection in drinks/food (perhaps specific spoiling or ripeness of food detection)
Blood analysis (a/b/ab +/-)
Sunlight analysis (dangerous uv levels)
Office/home etc lighting conditions
Air analysis (asbestos, smoke, fungal spores, carbon mono-oxide)
Time to have weekend now perhaps more idea’s in the future.