Hello.
The Raspberry Pi is a linux computer.
As such, you can do just about anything with it.
The software that does P-25 can just run on one.
It can run the open source Chirp just fine.
And, it is so small that it can be mounted on smaller monitors on back.
Walmart changed out their in-store display units a while back, the things you see at the ends of the shelves.
That is PERFECT for this!
Mount a set of AA rechargeable cells and you have a crappy laptop, sort of.
But, for programming talkies, APRS, P-25 monitoring, that type of thing, PERFECT!
True, you could do this with a laptop, but, are you willing to drill holes for a mount onto your laptop.
So, think of the Raspberry Pi as an inexpensive building block, a module that can be your gateway to learning.
Thank you.