If you really interested in a different perspective on crank lengths, read all of this.
https://biketestreviews.com/cranklength/
I ride 150mm cranks with a mid-foot position on the pedal and and I'm 74" tall and proportionally long legs and foot size. To put it into words the best I can say is it feels very efficient, maximizing what power I do have. That certainly was never realized using 170, 175 or 185mm cranks. If anything efficiency was worse the longer I went. After refining my fit over the years it seems to me all that matters is the ability to push the pedals down and back towards the rear wheel, as fast as possible given my ability. More crank length forward is going the wrong way as it makes that more difficult, at least for myself it does. Having short cranks and a mid-foot position also has compelled me to move my saddle much more forward than I ever imagined(35mm on one bike, 25 on another), which in turns makes for a low aero position feel natural. Not something I could ever do before for very long. Now I'm totally comfortable riding the drops all the time.
How I got here is long tall tale, so don't expect to just radically change anything overnight !
I can't help with anyone of sources of power meter type cranks as I use a square taper and a 110 and 110/74 BCD. They're not hard to find using any search engine.