Scare someone with a rubber spider or roach dropped right in front of their face! HalloWing with a PIR sensor and servo motor do your scaring for you!
You can turn a milk jug into a light diffusing, screaming, inner-lit skull filled with HalloWing-driven NeoPixels
Use one pair of glasses for normal, bright, and dark conditions, controlled by a Circuit Playground Express
You can program the new SAMD51 boards in Makecode, C++, and Python. How about Lisp or Forth? Why not?
Use MIT's App Inventor to easily make a killer Android UI that controls your Particle Photon or Electron Project.
Make a nightlight with just a Gemma M0 and CircuitPython! Or use a Circuit Playground Express for a super-featured version.