I was playing on my hardcore world on the newest snapshot, and was about to transport villagers into my house by going through the nether, but for some reason, they decided that teleportation was lame and would not go through the portal. Curious about this, I then went into a separate creative world and tested to see if any mobs or entities would go through besides the player. One image shows villagers, zombified piglins, and pigs failing to teleport, and the other shows items failing to do the same. (images were failing to attach, so here are some imgur links instead:
https://imgur.com/sYS4eyF
https://imgur.com/q0PfFB4 )