The algorithm used needs to be completely transparent and easy to review, and ideally have a way for the user to choose which news sources to follow.

Couldn't agree more.

Right now there's a concentration of only Left-wing propaganda sites flooding all the news aggregation feeds no matter where you go. And even if you attempt to "curate" the list they just replace whatever Lefty site you remove from the feed with a new one to replace it.

It's like removing a burnt piece of toast off the platter, but the waiter snidely replaces it with a burnt biscuit.