Not sure if this exists at all, privacy friendly or not, but it is something where privacy would be extremely important.
I would love to have some sort of application that allows the mapping of atomic (as in minimal) political statements and their logical relationships (e.g. if this is true then this other statement can't also be true) and evidence from media for their truth or falsehood. Probably also some sort of glossary of precise word definitions and which statement uses which of the definitions. This part should probably be done publicly and shared with other users apart from maybe a mechanism to obscure who added which information but this next part can not be public but lots of people would want the information. You should be able to mark each of those statements as something you agree with or not and then explore the implications of your opinions.
I feel something like that would be nice to replace the constant repetition of the same arguments on the same issues, especially if one could publicly link to individual statements from anywhere on the internet.
Didn't realize they had one, appears a lot of functionality requires an account to use. I'd be cautious overall based on the privacy practices they use in their mobile app, doesn't seem to be a big concern for them and I'd be careful giving them any trust. But if you do wish to use them, their mobile site with a good content blocker would definitely be the best option (preferably without an account if possible).