An idea I’ve been wanting to do for a while is to use an old phone as an IoT device. A second-hand smartphone is potentially a cheap way to get a processor, screen, and storage. The phone needs to be hackable – I think an operating system like LineageOS or JanOS needs to be installed on it. LineageOS has the best support for different phones. In order to be useful for IoT, the base phone should be extensible to add sensors or micro-controllers.
There’s a really interesting post over at The Verge on How to upgrade an iPod for 2018 with flash memory and a new battery. They say that the 5th Generation iPod works best, because it has the best DAC in it. They upgraded a 30GB iPod to have 250GB of storage and replaced the battery.
Of course, you could always just replace the SSD in your iPod to increase the size up to 1TB.