Tubes for use in ultrahigh pressure devices, and associated systems and methods of manufacture are disclosed herein. In one embodiment, a metal tube includes an elongate bore having a circular transverse cross-sectional shape. The metal tube also includes an elongate wall extending around the bore and having an annular transverse cross-sectional shape with an inner surface closest to the bore, an outer surface furthest from the bore, and a wall thickness extending from the inner surface to the outer surface. An inner portion of the wall is under swage-autofrettage-induced overall compressive stress.