The opposite of extreme leftism is not supporting Republicans or carrying water for Trump. It’s calling out those policies which are illogical or counterproductive. You’ve done this with your posts on nuclear power, which are fine–and you’ve found plenty of support for that on this board, which might indicate that it isn’t quite the echo chamber you say it is. There are all kinds of places where the Democrats don’t have things quite right, or where there is at least disagreement (see this thread for a short list of examples).
None of this implies embracing Trumpism or believing obvious Trumpist lies. Sam Harris said that Trump “has assaulted truth more than anyone in human history.” So maybe argue policy on its own terms instead of pretending that liberals are all of one mind that that you need to add Republican stupidity for balance.