(Children’s) book blogger and literary scholar Juli liest writes about Hallo!:
Welcoming people in a friendly way can be so easy – that is the simple message of Hallo! Simple, but with far reaching impact.
This is the complete review in German:
Hallo! Das Buch der zehn Freundlichkeiten
In addition, she also interviewed Barroux, see https://juliliest.net/2021/04/16/kinder-koennen-mit-buechern-traeumen-oder-auf-reisen-gehen/