Please refer to Wanderer (Genshin Impact) for details.
CN:「阿帽」
阿 is the article when calling people with familiarity. 帽(mào) meaning is hat and can also be read as a cat(猫/māo).
JP:「笠っち」
笠 meaning is hat. ~っち is a shortened form used by gals to refer to someone as 〇〇Chan. This is also commonly recognized as “Tamagotch” (a reference to the Tamagotchi).