Though I’m not a technical expert on these specifications, what you say sounds very similar to what I have also heard.

But, for some reason, I continuously hear that the Miyoo Mini (not the Plus) can be damaged by attempting to use a power adapter with too high voltage. I don’t have one (the original). The Plus also does come with a little flyer that says to never use any power adapter over 5v, even c to c. I’ve never broken that rule, just because I do not want to prove it to myself that they were correct and deal with all of that hassle.