All I am going to say is that your sister can use the Freestyle Libre without a reader. (But I don’t know if a reader from one country will work in another.)
See my review of how that could be set up here: FreeStyle Libre Flash Glucose Monitoring System - #24 by BK1112. I get my sensors from a friend in another country too, but then just use an app on my Android-based phone, which works well. Good luck!