Full block chests
There are a few resourcepacks out there trying to reimplement the alpha and beta Minecraft full block chest. Usually this is done using Custom Entity Models, either using Optifine or Fabric, but it's still an entity model.
Instead, we can use a mod called Enhanced Block Entities which turns chests (and other entities) into block models. This by itself makes the chests lag less since they are rendered as a block and not an entity, but we can now easily turn those 14x14 block models into 16x16, and disable the opening animation, to get that alpha/beta feel.
All this really does is that we can create separate textures for all the sides of chests.