This is similar to the question Can a Boggle use its Dimensional Rift in the mouth of a Bag of Holding?, which sparked a thought.
According to the boggle's statblock in Volo's Guide to Monsters (p. 128):
Dimensional Rift. As a bonus action, the boggle can create an invisible and immobile rift within an opening or frame it can see within 5 feet of it, provided that the space is no bigger than 10 feet on any side. The dimensional rift bridges the distance between that space and any point within 30 feet of it that the boggle can see or specify by distance and direction (such as "30 feet straight up"). While next to the rift, the boggle can see through it and is considered to be next to the destination as well, and anything the boggle puts through the rift (including a portion of its body) emerges at the destination. Only the boggle can use the rift, and it lasts until the end of the boggle's next turn.
We have a sprite traveling with the Boggle in our campaign. Could the Boggle pass the (Tiny) Sprite through the Rift?