Consider a Moore spectrum $S^n/p$. Has the $K$-theory of the extended powers of $S^n/p$ been computed?
For some context: equivalently, I'd like to have the free $E_\infty$-algebra over $KU$ on the $KU$-module $KU/p$. If we replace $S^n/p$ by $S^n$, then we do know the answer because of the theory of power operations over $KU$. Over $H \mathbb{F}_p$, these computations played an important role in the proof of Nishida's nilpotence theorem.