Comment by jwr

I am currently working on a Bluetooth Mesh home network allowing me to control lights, gather sensor data from various places, etc (think interfacing with a home alarm system for presence detection).

Also, a home air quality monitor, both with a display and reporting to my mesh network.

Or you could build a "plane radar" like this one :-) https://github.com/ironicbadger/ESP32-Plane-Radar