What would happen if you shot your pip boy? Would it explode? Or just break? Or soemthing diffent all together

depends on what you shoot it with. Are we talking big guns, small guns, energy weapons or a mesmetron?

....Any?

considering how every character's pip boys never break despite being shot at millions of times im saying its made out of some futuristic material that never breaks

There made out of Chuck Norris' bones,of course they never break.

But that just raises another question; how did someone manage on getting their hands on his bones? They're even more rare than the Holy Grail.

It's probably made of some indestructible materials. Although I would imagine that the screen would at least get a scratch or two...

If the Pip-Boy can take so many hits, then they should make an armor out of it. It would be called...Gods Power Armor...SWEET!!!

I'm pretty sure it's a gameplay limitation - and not that they're meant to be indestructable.

If the devs didn't have to worry about hand-holding so much (though I must admit, it's nowhere near as bad as Oblivion), they might have made it so you had to repair it and everything.

To be honest, I would like to see that, it would add more realism to the game and it'd be a good way of solving the hand-holding problem that people complain about.
Did you also notice that the arm with your Pipboy never leaves your body? Even if the rest of your limbs get blown off?