In forthcoming joint work with Christoph Kehle, we present a PDE-based proof that for any Einstein--Maxwell--matter system satisfying the local mass-charge inequality, corresponding to $\mathfrak{m}^2 \geq \mathfrak{e}^2$ for charged massive dust, any solution arising in gravitational collapse from spherically symmetric data on $\mathbb R^3$ cannot settle down (in a suitable sense) to an extremal Reissner--Nordström black hole. This generalizes a recent result of Reall (2024), who proved, using spinor methods, that extremal Reissner--Nordström cannot form in finite advanced time if the matter satisfies the mass-charge inequality. Moreover, we prove the sharpness of the mass-charge inequality: for any $\mathfrak{m}^2<\mathfrak{e}^2$, we construct smooth, one-ended, asymptotically flat Cauchy data for the Einstein--Maxwell massive charged dust model whose maximal future development contains a black hole with an event horizon that becomes exactly extremal Reissner--Nordström at finite advanced times.