I would be against it. I am a marxist and would probably have great debates there but the amount of toxicity will never be contained. I am 100% sure most will try to troll us and downplay climate change as gardening.
There's so much variety in leftism that federating with people that basically think there are only a few relevant movements won't be a very fun encounter. They should just host a lemmy for each of their union and federate if it's the beginning and end of their worldview IMO, then I'll consider federating with some of them.