Not shockwave (LiSWT) or ultrasound alone. It's a combination of liSWT, ultrasound, and active traction during healing processes. There are various data supporting since 2015, and the earliest was 2011 as experimental processes using focused wave frequencies between 2Hz to 44MHz (not kHz). The international teams are still focusing between 2Hz to 4Hz, pushing at 104F (40C) to 106F (41.2C), followed by 1 to 1.5kg traction for 6 hours. There are a few successes, but the successes dropped below 20%. They also tested between 4kHz and 44MHz, the same temperature range, and the successes still reported 20% and less. Most testing ranges fall between 50kHz and 5Mhz, and when the candidates were offered the options, they chose 1MHz (deeper penetration across the entire penis) to 3MHz (shallow for addressing Peyronie's issues). The pools of candidates are very small because of the clinical costs, since those machines are crazy expensive to have at home.
There are brothers here who purchased older ultrasound machines with 4MHz to 12MHz capacity and used them at home. Some saw gains during the first 120 days, but inconsistencies slowed or halted those gains. The gains were reported between 0 and 1cm, but no additional reports were provided afterward.