Asklemmy

Perhaps surprisingly when it comes to breaking the echo chamber and having diverse political points of view and approaches (on subjects like identity politics, intersectionality, geo politics, organization building, strategy...etc) I'd say even ML circles have a lot more of that than just vaguely leftist safe liberal stances (at the very least they might have novel ideas and no orange man bad meme).

If you want more diversity of opinions you can expand in different directions, but I hardly see what good would be a place that has both fascists and anti-fascists for example and most of us are tired of picking internet fights. I suppose as long as you're aware of which kind of discussion you've more tolerance for you're good, but whether it's tolerance for the occasional black crime rate statistic or an esoteric graph of the falling rate of profit, you're not likely to find a space that has both.

In general I'd go with Cowbee's recommendations though (for something that's still obviously fairly leftwing)