You're welcome!
It was a crazy chance that I came across a picture online that made me think maybe Rebutia krainziana (now I know that's a var. not a species). I googled Rebutia minuscula and came across a picture that was labeled Rebutia krainziana.
I'm just glad I stumbled across it because so many species of cacti look almost identical and it can be difficult to narrow down a species (and when you start getting into cultivars, oh boy).
That's possible about being related, I don't really know much about Rebutia to be honest. I just know I love their flowers lol.
Planto