When Miitomo came out, I thought finally, Nintendo had got a clue about online services, made someplace that could be a hub for your "Nintendo identity", let you make custom Miis to play in other games, or even use as avatars for other places, hook up chat and friends list for all other Nintendo games…
But, none of that happened. It stayed a small closed service that connected to nothing, never let you do more than change clothes, change the wallpaper and flooring of your tiny empty room, and chatter at annoying questions, the talking people do when they have nothing to say.
Animal Crossing: Pocket Camp has its own much more primitive avatars and limited set of clothing, at least it's active for now, but there's very little "social" to it.
Some years ago, I went into Line Play with someone, and despite spending no money, just freebie coins, I ended up decorating this house, which is still there (had to stitch some screenshots together, there's no "photograph whole room", only a video capture). This is what Miitomo should've been like: