Have their performance suddenly dropped like crazy?
Can you no longer use them for the purpose for which you got them?
If no, then why bin them?
Two years ago, my dad and me set up a new project with a raspberry pi zero w, it is a water temperature meter to report the water temp at a swimming hole my dad enjoy.
The Pi has a DS18B20 temperature sensor and is powered by a motorcycle battery through a timer, every half hour the timer turns on the Pi, it boots Raspbian, runs a bash script that grabs the temperature value, sanitizes the data, checks it for errors, sends it to a webpage, waits 30 sec, and then shuts down the pi.
Just because there are more powerful options doesn't make your existing devices less powerful.