  Let $(X,\nu,T)$ be a measure-preserving system, and let $P_1,\ldots, P_k$ be
polynomials with integer coefficients. We prove that, for any $f_1,\ldots,
f_k\in L^{\infty}(X)$, the M\"obius-weighted polynomial multiple ergodic
averages \begin{align*}\frac{1}{N}\sum_{n\leq N}\mu(n)f_1(T^{P_1(n)}x)\cdots
f_k(T^{P_k(n)}x) \end{align*} converge to $0$ pointwise almost everywhere.
Specialising to $P_1(y)=y, P_2(y)=2y$, this solves a problem of Frantzikinakis.
We also prove pointwise convergence for a more general class of multiplicative
weights for multiple ergodic averages involving distinct degree polynomials.
For the proofs we establish some quantitative generalised von Neumann theorems
for polynomial configurations that are of independent interest.
