Here are some I would have use for + 2 extra
Idea #1: background application like Glance screen, but it shows either non-functional lock screen (power button / double tap required to get to the actual lock screen with interaction and unlock) or actual lock screen (like if power button was pressed) when proximity sensor goes from "near" to "far" and display is off. Like full glance on every device
Idea #2: Camera app with proper living images implementation. e.g. capture x frames / second from preview stream to a buffer starting from start or focus lock untill image is captured. Create mp4 video from buffer (use final frame as reference to align buffered images -> stable video) and merge it with image (or however it is done) to get W10 living image.
Idea #3: Selfie camera app where screen acts as light/flash. Light temperature could be changed or automatically detected from preview stream -> lit face looks correct compared to background / ambient light. Unless it is possible to programmatically set screen brightness / back light to maximum, this might have no effect. LCD is poor torch...
Idea #4: NFC / barcode counter. When NFC or barcode / 2D code is read, increase count and keep log with timestamp. Get name for it on the first time. Usage: how many times RC car lipo battery is charged (with 2 similar batteries manufacturers barcode cannot be used
), when security / sanity personnel has checked some area (requirements for security?). This might need a bit of improvement
Idea #5: Driving logbook which takes distance from GPS + possibility to take picture from odometer at start and end with OCR to extract the reading.