I wonder if unicorns, and myb just myb pegasi, would come via cross pack integration? Or it they would come later with fairies? Became either could be options. But I think since we're getting horses now, that any horse offshoots should probably come at the same time. Especially since we already have a bunch of magical packs.
On the other hand if the fairies gp (since it seems it will be a game pack) really focuses on the magic of it all, and also ??fixes issues with other magical beings that could be classified as fae adjacent like mermaids; then it might be possible/even expected to get the other horse forms then. After we've already gotten used to them a bit and they fixed the inevitable bugs. And maybe even get more types of mounts.
I think all the occults could have their own horses. Like get a skeleton horse for Grimm. A blood drinking horse for vampires. A Pegasus for spell casters. A giant seahorse or a waterhorse/kelpie (might be better and more horselike) for mermaids. Werewolves would need just really stalwart horses that aren't afraid. And the unicorns/binicorns might only show themselves once the fairies do. Idk what aliens ride but they're trying to blend in so probably just a horse.