The work represents the theoretical modeling of the electrical conductance in the nanoscale interconnects within approach of the extended point-like contact (PC) model. The approach describes a diffusive, quasi-ballistic, ballistic and quantum regimes of the spinresolved conductance, that is important for the development of the heterojunction models, including 2D -3D interconnects. As a benefit, the model provides a unified description of the contact resistance from Maxwell diffusive through the ballistic to a purely quantum transport regimes without residual terms. The model of the PC assumes that the contact area can be replaced by a complex quantum device, e.g. single tunnel junction, narrow magnetic domain wall (DW), vacuum gap between tip and surface, source to drain transistor's channel, etc. The potential energy landscape of the device determines its electrical properties.