  Two-dimensional van der Waals materials have recently been established
experimentally as a highly-tunable condensed matter platform, facilitating the
controlled manipulation of band structures and interactions. In several of
these materials, Dirac cones are present in the low-energy regime near the
Fermi level. Thus, fermionic excitations emerging in these materials close to
the Dirac cones have a linear dispersion relation near the Fermi surface as
massless relativistic Dirac fermions. Here, we study low-energy fermionic
excitations of such Dirac materials in the presence of a mass gap that may be
generated by symmetry breaking. Introducing a dynamical Fermi velocity and/or
time-dependent mass gap for the Dirac quasiparticles, we exhibit the emergence
of an analog of cosmological fermion pair production in terms of observables
such as the expected occupation number or two-point correlation functions. We
find that it is necessary and sufficient for quasiparticle production that only
the ratio between the mass gap and the Fermi velocity is time-dependent. In
this way, we establish that highly-tunable Dirac materials can serve as analog
models for cosmological spacetime geometries, in particular, for
Friedmann-Lema\^itre-Robertson-Walker expanding cosmologies. We briefly discuss
possibilities for experimental realization
