Raspberry Pi Zero W is a SBC with less computing power than Raspberry Pi but good enough for small IoT projects and firing up Linux.
Power DockA-la-carte price: $15.00The Power Dock provides power to the Omega2 via a lithium polymer battery. Expansion DockA-la-carte price: $15.
I found the best video for starting your Raspberry Pi experience from unboxing to firing up OS. It also tells you about each hardware parts.