For GPIO on mini PC you can use USB-GPIO adapter. Under Linux it can be used like native Raspberry's GPIOs.
Raspberry is great when one learns or needs a typical, embedded platform. I'm using Raspberry to learn about Kernel, drivers, bootloaders, etc., but I wouldn't use it as my local server/home automation computer. For this, I have a second-hand HP T630 that I bought for $46, and works great.
How does Raspberry teach anything about bootloaders? It's probably unique, it functions completely different compared to all other bootloaders and it's closed source.
Raspberry is great when one learns or needs a typical, embedded platform. I'm using Raspberry to learn about Kernel, drivers, bootloaders, etc., but I wouldn't use it as my local server/home automation computer. For this, I have a second-hand HP T630 that I bought for $46, and works great.