  We present exploratory analyses of the 3D gluon content of the proton via a
study of unpolarized and polarized gluon TMDs at twist-2, calculated in a
spectator model for the parent nucleon. Our approach embodies a flexible
parametrization for the spectator-mass function, suited to describe both
moderate and small-$x$ effects. All these studies can serve as a useful
guidance in the investigation of the gluon dynamics inside nucleons and nuclei,
which constitutes one of the major goals of new-generation colliding machines,
as the EIC, the HL-LHC, NICA, and the FPF.
