GIANT LITTLE ONES is a solid film, the kind that is great to discuss as it successfully does something that most films (unfortunately) don't do: it re-incorporates its themes throughout in big and small ways with major and minor characters.
For example: You'd think that the minor character Mouse is meant to be nothing more than comic relief and a throwaway character (meaning that the screenwriter could omit Mouse from the script, and the rest of the film would not be harmed significantly for that loss), but you'd be wrong; she is enormously important in relating the movie's core Theme.
Mouse makes Franky really think about the value of owning one's sexuality, and she cites examples of people who don't care what others think about them and, as a result, they are respected for their confidence and ownership of Self. And she is an example of accepting others as they wish to be seen without question -- a lesson that other characters need to learn including Franky (our protagonist).
The relationship between Franky and his father for much of the film seems stagnant and forever distant, but it's not. It takes a long time, but watch as it starts to shift; it is indicative of a shift in Franky's perceptions about his own sexual fluidity... AND his ability to own it. In other words, he takes Mouse's words to heart and, in time, he owns his sexuality -- whatever it may be.
Not knowing what happened between Franky and Ballas in bed is an excellent directorial choice because, like the other characters, we don't actually know the truth for quite a while. So, like the other kids at school, we can only assume (perhaps incorrectly) who did what to whom; we don't actually know the truth. And neither Franky nor Ballas know or acknowledge their own truths.
And the ending is terrific. It is not neatly tying up all the loose ends of Franky's relationship with Ballas (as most people expect and/or want) because, at its core, the film isn't about that. This film is about the acts of Ownership (particularly of Franky's ownership of his own sexuality) and Acceptance (particularly of his dad and Ballas).
In the end, Franky recognizes that Ballas has had extreme difficulty owning his own sexuality. Franky can finally see that Ballas is suffering, and he lets Ballas know that he is aware of that... but loves him anyway, as a friend... and maybe more (though, again, that doesn't matter).
Franky matures enormously through this film, and we know by its conclusion that after this movie is over, he will be patient person with others and make an excellent friend, an excellent sexual partner and an excellent father. In his confidence, he is owning Self and accepting of others.
And a final thought about the title -- I don't think it's a reference to growing up ("little ones" being kids). I have a sense that "little ones" refers to the cautious baby steps we take in life, and sometimes we need to take giant, confident grown-up steps in life in order to change for the better.