I will describe a new portal to the dark sector that is a topological interaction, similar in structure to the WZW term in QCD. This portal connects pions and photons to a pair of dark matter (DM) pions, and can explain the observed DM relic abundance for GeV dark pion mass. Its topological nature implies the absence of signals in direct or indirect detection experiments despite the low-ish scale, consistent with observation. From the EFT perspective, this interaction is an unusual example of a quantised topological term that does not match an anomaly. Rather, it encodes a generalised symmetry structure known as 2-group symmetry. Matching this generalised symmetry guides our building a TeV-scale completion for the topological portal, which is here essential to make predictions for colliders like the LHC. I will conclude by putting this model in a broader context of possible topological couplings to dark sectors, some of which seem to arise naturally from string theory.