  We explore a toy model mechanism of geometric cancellation, alleviating the
(classical) cosmological constant problem. To do so, we assume at primordial
times that vacuum energy fuels an inflationary quadratic hilltop potential
nonminimally coupled to gravity through a standard Yukawa-like interacting
term, whose background lies on a perturbed Friedmann-Robertson-Walker metric.
We demonstrate how vacuum energy release transforms into geometric particles,
adopting a quasi-de Sitter phase where we compute the expected particle density
and mass ranges. Perturbations are introduced by means of the usual
external-field appproximation, so that the back-reaction of the created
particles on the geometry is not considered here. We discuss the limitations of
this approach and we also suggest possible refinements. We then propose the
most suitable dark matter candidates, showing under which circumstances we can
interpret dark matter as constituted by geometric quasiparticles. We confront
our predictions with quantum particle production and constraints made using a
Higgs portal. In addition, the role of the bare cosmological constant is
reinterpreted to speed up the universe today. Thus, consequences on the
standard $\Lambda$CDM paradigm are critically highlighted, showing how both
coincidence and fine-tuning issues can be healed requiring the Israel-Darmois
matching conditions between our involved inhomogeneous and homogeneous phases.
