Or, have I totally misunderstood what you've said?Sort of. Do your experiment (build a linux box) and put it in front of a kid with no exposure to computers (other than as appliances) try this with kids from 6 to 16.
As you get toward 16 you will start getting better engagement, most will figure its too confusing and stop.
I've run the experiment with Arduinio, even with its pretty straight forward GUI there is still some serious complexities around the notion of compiling, downloading, driver compatibility, etc etc.
One of the things I will do with a RasberryPi is look at building an embedded BASIC box. Hook a keyboard to it, plug it into a TV's HDMI port and turn it on. Blammo, BASIC prompt. (If I can swing it it would be a Python prompt but I digress). Type in the code (using BASIC syntax sorry)
100 CLEAR
110 DRAW(100, 100, 200, 100, "WHITE")
120 DRAW(200, 100, 200, 200, "WHITE")
130 DRAW(100, 200, 200, 200, "WHITE")
140 DRAW(100, 100, 100, 200, "WHITE")
150 FOR I = 100 TO 200 STEP 10
160 FOR K = 200 TO 100 STEP -10
170 DRAW(I, K, K, I, "BLUE")
180 DRAW(K, I, I, K, "GREEN")
190 NEXT K
200 NEXT I
210 END
Type run, and blammo, drawing pictures on a screen.
Why pictures? Being able to draw graphics is a compelling thing for folks, they like to do it, it touches their inner finger painting. It compels them to think about 'steps' and 'math' and stuff.
Doing graphics in Linux is a PITA. The notion of a system which throws away everything except a way to explore through programming, and has access to all of the capabilities of that system, is key. The programming needs to be accessible. I could be K&R C as easily as BASIC but it would need a very simple build environment (code for NOT gcc).
Something that with a manual of no more than a couple of hundred pages, can engage a student to explore it with programming. They don't know what programming is so complaining about types (for example) just demotivates them.