I wonder if this shouldn't be its own genre. Ever since Ruth Krauss did A Hole is to Dig, it seems like the book based on child interviews is a 'thing'. This could be called a concept book, but it's really more of an inquiry book. The main effort of the character is to learn more.
Gabi Swiatowska's illustrations make this book what it is. It's got a somewhat dark tone to it, because of the overall palette she chooses, which is unusual and interesting. Her figures seem like close studies of Dusan Kallay's illustrations--there's even one page where the grandma's fingers close in a Buddhist iconic sign which is something I've seen Kallay do many times. Mostly it's the faces that hark to Kallay's work. Swiatowska tempers the dark palette with colorful elements that really stand out by contrast on each page.