Bear with me on this one. What really makes the Raspberry Pi what it is? Linux? No, because there are plenty of machines the open source OS will run on. Linux is a Unix derivative; the basis of macOS is FreeBSD, also a Unix derivative.
Sure the Pi is only 40 quid and small, but for me what really makes the Pi stand out from all those laptop and desktop computers is the fact that it makes its microcontroller’s GPIO pins readily accessible through a handy set of header pins. Unlike all ‘serious’ micros, it’s perfect for connecting to and controlling a whole stack of add-ons, including sensors, displays inputs and actuators.
When it comes to hacking hardware there’s an easy way and there’s a hard way.
The hard way involves connecting peripherals direct to one of the standard buses supported by your Raspberry Pi, Arduino, Beaglebone or whatever. Buses like I²C, SPI, UART and 1-Wire. You’ll need to take care with your wiring: have you got the right pull-up or pull-down resistor? Is there too much capacitance in the line?