  The use of sub-Terahertz (sub-THz) band is gaining considerable attention in
6G networks. In this study, we introduce hardware and propagation integrated 3D
Propagation Model to describe sub-THz channels and discuss its advantages over
both deterministic and stochastic 6G channel models. The unexplored mutuality
of localization and communication is presented and its potential in integrated
sensing and communication (ISAC) applications is highlighted. Afterward, a
real-time sub-THz localization experiment is conducted to show the impact of
the mispositioned and misaligned narrow beams on service quality. In
continuation, we highlight the most current challenges and developments in THz
localization and explore the potential of sub-THz frequencies to efficiently
utilize the ultra-wideband spectrum. In the end, the open issues that need to
be overcome to provide high spatial resolution and millidegree-level angle of
arrival estimation in ISAC applications have been explored.
