I don't know what it is, I don't know if he wrote it, and I don't know if this is legit, but World of Reel's Jordan Ruimy reports that Charlie is lined up to direct a film called Later the War with Sarah Green linked as a producer.

Two notable pieces of evidence have Kaufman’s “Later the War” starting production in 2025. Sarah Green is being linked as producer on this new film which might have gotten a grant from the Polish Institute of Film. Word is that it was secretly shopped around this month at EFM Berlin. (Source)

Personally I wish his take on IQ83 would go into production. Technically it's an adaptation, but really it's an original script with the novel as a loose inspiration.

Thanks u/pavingmomentum and Bart!