In this work, we highlight the existence of a lower limit on the tidal deformability parameter $\Lambda$ for static, isotropic compact objects. Additionally, by considering the corresponding upper bound on compactness, we identify the region within the compactness–tidal-deformability parameter space where physically motivated exotic compact objects could potentially reside. Our analysis reveals the presence of a {} between black holes, characterized by vanishing tidal deformability, and horizonless compact objects. Prompted by this finding, we investigate the possibility that a population of maximally compact exotic objects described by a linear equation of state may simultaneously inhabit the lower mass gap and the sub-solar region, thus qualifying as (primordial) black-hole mimickers while distinguishing themselves from the latter through their nonzero tidal deformability. We also provide an illustrative estimate of the prospects for probing their tidal response with present and future gravitational-wave detectors. Finally, considering solitonic boson stars as explicit field-theoretical exotic compact objects whose bulk structure approximately reproduces the linear equation of state, we show that values of $\Lambda$ below the isotropic limit can be reached without violating relativistic causality. This result reflects the relaxation of the isotropic perfect-fluid and sharp-surface assumptions: the dominant energy condition remains satisfied, whereas the strong energy condition is locally violated near the effective surface.