https://projects.raspberrypi.org/en/projects/fart-detector
"All kids understand that farts are funny. As we grow older, some of us lose our sense of humour in this area. You’ll be glad to hear that we believe that building a real working fart detector has both educational and comedic value."
https://projects.raspberrypi.org/en/projects/build-your-own-weather-station
If you have some of the measuring implements for the Raspberry Pi Weather Station but not the HAT (which was only distributed to schools), then this page will show you how to actually use the damn things.
https://coral.ai/projects/bird-feeder
This project teaches you how to build a smart bird feeder that uses an image classification model to identify birds and animals frequenting the feeder, records their visits, and deters squirrels from stealing bird seed.

https://www.instructables.com/id/PiAnyWhere-4G-LTE-Hat-for-the-Raspberry-Pi
IOT BIT (Formally Known As PiAnywhere V1.31) 4G & LTE Hat for the Raspberry Pi : IOT BIT 4G & LTE Hat for the Raspberry Pi 4G (100 mbps down/ 50 mbps up) – Ultra fast internet connectivity for your raspberry pi, excellent for large downloads and video streaming. TheIOT BIT 4G & LTE Hat for the Raspberry Pi Beta provides …

Makes cool projects, including Linger, for dicking with public WiFi surveillance.

https://learn.adafruit.com/raspberry-pi-physical-dashboard?view=all
Making a funky 1970s-sci-fi-style readout with a Pi and some 7SDs/motors.

https://www.hackster.io/jacquin-buchanan/intellisaurus-dinosaur-robot-kit-662245
An open source kit to build a walking smart robot dinosaur. By Jacquin Buchanan.