I don’t know if they were canceled or intentionally short runs, but two shows my kid watched that I ended up loving: Gravity Falls (2 seasons) and Owl House (2.5 seasons). Both ended flawlessly if you ask me, but I would have enjoyed more.

Gravity Falls was intended to be a two-season run. Owl House was supposed to be three seasons, and was shortened from a three-season run to the three extended episode third season. The creators of both shows are (or were, I don't keep on this stuff) romantic partners, which is fun.