One year for Christmas, Miu gave Kiibo upgrades that benefited their classmates

Kaede: metronome
Saihara: crime scene analyser
Kokichi: Panta dispenser
Tenko: Reinforced Armor to absorb her blows
Ryoma: Tennis ball machine
Kirumi: Vaccum cleaner
Angie: a stereo system that played songs and prayers praising Atua
Korekiyo: an audio encyclopedia of human culture
Gonta: High powered camera for taking bug photos
Kaito: One of those nightlights that turn the ceiling into a starry sky
Tsumugi: nothing really, he already was a perfect mannequin
Himiko: a voice control app which makes Kiibo the perfect assistant (or butler when she's feeling lazy)

(Miu didn't know what upgrades Maki or Rantaro would like so she just gave them gift cards)