There is no better way to learn about electronics and technology than building your own things. Adafruit has shared a guide that shows you how to 3D print and build your own portable mini PC. It has a 7 inch display, a built-in battery, and HDMI connectivity.
The device has built-in USB charging. As Adafruit suggests, this can be used to interact with 3D printers but you can also use it to manage your smartphone or perform other tasks. You are going to need a Kangaroo desktop, 7″ HDMI display, battery, switch, and a few other parts to get started.