I believe the internet is contributing to echo chambers because of filter bubbles.People hear what they want to hear. If they are intentionally seeking out (or actively trying to create) echo chambers, you can't really stop that.
Additionally, studies consistently show that most people are pro choice. They also consistently show that most people are anti abortion.
In other words, no one is pro abortion. No one is "for killing unborn babies." But some people frame the political policies in terms of rights of the mother to choose and some frame it in terms of rights of the unborn to live.
There is no easy answer here. Pretty much everyone thinks that abortion should be a last resort, not some kind of primary method of birth control. But there is enormous fighting about exactly where and how to draw the line on who, what, when, where and how.
So one of the problems you will find is that when you try to get "both sides" of any argument (abortion is merely one example here):
A) Either they are talking about very different foundational ideas such that it is kind of disingenuous to frame them as "opposing arguments" or
B) You have a set of people with such narrow views that they can only conceive of two possible options here and the real answer is to be looking for "a third way."
I think a better answer is to write about a broader point of view that helps promote a non-binary conversation and thought process and that helps promote that "third way" that has some hope of addressing real concerns for "both sides."
It's extremely problematic to try to divide more than 300 million people into two camps and pretend that the millions of individuals making up each "camp" all uniformly agree with each other. Yes, people choose sides in order to try to exercise power. But that doesn't mean the camps really authentically represent the full views and sets of positions of any of their members, much less all (of their members).
I think your desire to create this is rooted in good intentions, but I suspect that something like this will just help entrench the "war" by further promoting the idea that there are, in fact, two camps and only two camps and every American needs to choose one. I realize that is not what you desire to do, but that may well be the result.
I find that trying to have meaningful and nuanced discussion with almost anyone at all (other than my sons) is incredibly hard because most people want to peg me as either "for" what they are for or "against" them. This leaves no room for positing a third way at all, much less a potential fourth, fifth or Nth way.
I choose to blog as my small pebble of contribution towards trying to combat the either/or thinking and trying to posit new mental models for old problems.
If you do start something, I would be happy to give feedback or have some kind of limited (probably short term/one time) role in its development. I am not looking for an on-going time commitment. Furthermore, although I support your position that it "will be" open source, I see zero reason why this must be non-profit. I think this is just another example of common thought patterns that somehow being non-profit means it will be done for the right reasons, in the right way, etc and this is absolutely not in any way guaranteed.