Alle unsere Freunde aus ganz Deutschland
translates to
All our friends from all over Germany
Can I use ganz unsere Freunde aus ganz Deutschland
If not both sentences(with ganz unsere) above and below have the same meaning?
Sie leben sehr harmonisch und sind sicher ganz unsere Freunde
Here the meaning is They live very harmoniously and are certainly very much our friends
"Ganz unsere Freunde aus ganz Deutschland" sounds at least strange or awkward, doesn't mean what you intend it to mean and one can argue it's wrong:
The meaning of that translates to English as "Completely our friends from all over Germany". It gives rise to the suspicion that the friendship might not be so well-founded after all.
The same suspicion would arise in the sentence "Sie leben sehr harmonisch und sind sicher ganz unsere Freunde". Are you really sure they are completely your friend?
Now what's the issue? The issue is that friends are countable. So you cannot refer to a countable number of people or things as "Ganze Leute" or "Ganze Dinge". For countable things and sets, it's 'alle': 'Alle Freunde', 'Alle Äpfel' (all apples), 'Alle Worte' (all words).
Friendship on the other hand is uncountable. So the 'Ganze Freunde' has to be interpreted in a way that the 'ganz' refers to the level of friendship of the people in question. So a wording like "Die ganze Freundschaft beruht auf dem gleichen Humor" is perfectly fine (the complete friendship is founded on the same kind of humor). Similarily different meaning has thus 'Ganze Äpfel' (complete apples, not cut or damaged), 'Ganze Worte' (complete words, not just a few letters not forming words).
I don't even want to venture into a terrain where a sentence like "Ganze Leute liefen die Straße entlang" can be formed. The images of what the other people do are not nice.
"Ganz" in this usage (there are others) means something along the lines of "complete" or "whole". So, your idea is a bit off, I'm afraid ;)
If you take
Alle unsere Freunde aus ganz Deutschland
the idea is basically like this: You take the region the first friend is from, and combine with the region the second friend is from, and combine that with the region the third friend is from, and so on. At the end, you have "the whole of Germany", because the friends are from all over Germany. You could also say, the combined regions cover Germany completely.
As you see, to use "ganz" like this, there has to be some kind of definition at what point something is complete. But what would a "complete friendship" even be, say in comparison to a 95% complete friendship? ;) So, you can't use "ganz" like this to express something like "very".
As a side note, you (probably accidental) almost stumbled across a way you can use "ganz": "sicher ganz" doesn't work, but "ganz sicher" does. It basically means "completely certain":
Sie sind ganz sicher unsere Freunde.
They are completely certain our friends.
