The (maybe?) newest ones, the Tamagotchi Unis, had some special versions come out that kind of have a "DLC" that changes the Tamagotchi a bit. Like, there's a monster themed one, but it's really just a normal Uni that gets a new monster location and adds new Tama chains for what they can grow into. I say dlc because it comes with the card when you buy the monster Tamagotchi, but you can also get the code to change any of the units into a monster one.
Id take aesthetic DLC over NFTs and micro transactions any day, so I'd say it's pretty cool still