While working on the previous Aurora image, at one point I had the A Hat In Time ost playing, and thought about how it would be fun to have Aurora stumble across a ponified Hat Kid as some sort of easter-egg appearance. Thinking about it more, I thought it would actually make more sense for "Hat Filly" to be a character that regularly re-appears and gives Aurora and her part side-quests. Specifically quests to gather up Hat Filly's missing Timepieces, in exchange for statuettes of the Mane 6 she had stumbled across.
Basically, Aurora's story would be littered with side-quests between the larger plot stuff (mostly so the party has something to do in the "downtime" while they wait for other characters and other developments to occur). This being how Aurora and the party come into possession of upgrades to stats and gear, instead of just randomly finding good stuff out in the wasteland.