It's interesting to me. Perhaps a reasonable way to verify the Amps of a charger. Maybe a way to see what kind of draw a device has on your USB bus. I can think of ways to use one. I eagerly await your thoughts on it once you get it.
It occured to me that I had another potential use. I bought long USB charging cables that have been wonky at best. It would be nice to see how they test out for power. I realize that this does little to check data integrity but still...
ED. I like the first one you listed. That second one would be a hot mess in my hands.
1st pic, can't see anything from the flash, 2nd pic with flash off, you can see it. Works great. I have a WD 1TB USB 3.0 HDD hooked up and at it's peak current use, it peaked at .7 amps when copying a large file, when not reading or writing it draws .22 amps