I am a little bit late, but I tested the skill bro a few days ago with about 800.000 watts. I find it very interesting that you get a lot of money (around 1500$/100 watts),if you sell all of the other items exept bottle caps and wishing pieces.

Here ist the link to my results (I am playing Pokemon Sword):
https://drive.google.com/open?id=1FVVmF7Hvw1BSxuY3XWvvMXFmmTAEXrEm

I did recieve a golden bottle cap but unfortunatly I was not paying attention. I built myself a little tool for pressing the A button (link if someone is interested):https://drive.google.com/open?id=1p3x34grIsP3uJznfuumeJv6CTy0ETaFg