Villagers gradually transform into Piglins in the Nether

Unlike the player, villagers who cross through a nether portal retain their ability to sleep in beds and tell day from night.

But what if that was only temporary? Here's my suggestion:

Any villager who spends 7 nights in the Nether grows piglin ears and begins wearing a gold nose ring. These half-transformed villagers also trade for gold instead of emeralds, with slightly different trades than their Overworld counterparts. However, they can still return to the Overworld without being zombified, and spending 7 nights in the Overworld will turn them back into regular villagers.

Any half-transformed villager who spends another 7 nights in the Nether fully transforms into a Piglin and loses their ability to return to the Overworld or use a bed. However, depending on their job at time of transformation, they permanently retain a unique piglin trade item.

If a player wants to avoid this, a Golden Dandelion could be used on an adult villager to make them immune to transformation, or on a half-transformed villager to permanently keep them in that state even if they return to the overworld. In this case, it also makes sense to allow the player to use Golden Dandelions on Piglins to make them immune to zombification before they enter the Overworld.