We need more explicitly socialist fiction
Fiction helps put ideas into the mainstream. As the late Mark Fisher stated in one of the essays in his k-punk saga, we shouldn't avoid the mainstream as intellectuals.
Socialist fiction doesn't have to be utopian, but it can and should explore more nuanced ideas where previous takes of socialism in fiction didn't go far enough: the identity of the revolutionary, forming solidarity, triumphing over seemingly unstoppable forces. Socialist fiction can even be pessimistic, show how anti-communist social attitudes allow for catastrophic developments to occur, either for the characters involved or for the world as a whole.
I'd refrain from relying on citing theory too heavily in the writings, and instead use what we've learned from theory to guide the perspective of the narrative, and how it influences the decisions of our characters in the world.
For example, I'm writing an alt-history cyberpunk story about a class war, following a cast of characters navigate a climate crisis, trans identity, the legacy of anti-blackness and anti-communism in the near-alterfuture of the story, and the intrinsic interconnection between these struggles.
We need socialist fighters, writers, thinkers, and organizers. We need to realize the separation of ideology is a moot point, each flavor of socialist has something necessary to add to the table of techniques, anarchists have street power, communists have organizational will, etc. We're all fighting for a classless, stateless, moneyless society. This isn't so much "left unity" as a call for a broader socialist collaboration.