This article examines the promising potential of indium phosphide (InP) devices with 500 GHz or higher fτ and fmax performance for 100-340 GHz 6G applications. Heterojunction bipolar transistors (HBTs) in 6G power amplifier applications demonstrate record 15.3 dBm Psat performance in the laboratory with 32% power-added efficiency (PAD) at 130 GHz. High-electron mobility transistors (HEMTs) in RF front end applications demonstrate 0.60-0.75 THz fτ and 1.1-1.5 THz fmax performance. Device scaling and higher levels of integration to improve performance at higher frequencies and first-pass yields for commercialization require improved modeling technologies and some modification of process flows.