Loyalty tridents (work, but visual projectile is a retextured arrow).
Crying obsidian (respawn anchors not implemented—just decor).
Piglins (bartering works, but they don’t attack if you open chests).
What works: You can often find texture packs and mods that bring the 1.16 visual aesthetic (textures, UI, menus) to the game.
What doesn't: If you are expecting a seamless, official 1.16 Nether experience with new mobs spawning naturally and generating massive caves, you will be disappointed. It is usually a "skin" of 1.16 over 1.8 mechanics.