If anything the next new playable race needs to be a tiny race so we have a smol option that isn't a potato.

Loporrits
Ivalician Moogles
Whatever you want to call Korone's Furball form
Something inhuman like Faputa from Made in Abyss

Playable Loporrit I can actually think of a few ways to work it lore wise having one as the bunny of light from the start of ARR since the story experience pretends every other player character doesn't exist. Tweaking a few CS'es to add a reaction to the strange talking rabbit that can't remember it's past before the event that kicked off ARR and later in Endwalker getting chewed out for leaving the moon and losing your memory. I mean we run across one planning to leave the moon while we're up there and there's bits and pieces of lore indicating they've gotten to ethirys before. I honestly don't even care if they can't wear most headgear due to their ears and face shape. It would just mean they complete the size set started by Viera and Hrothgar lol.