An API option to send an entity spawn/despawn event to a player via packets would be useful.

I have used this in the past to create Hologram's by sending a player an armorstand spawn packet via nms.

I find this approach better than spawning in an actual armostand since its less error prone (the packets are all client side so there is no chance that you will have duplicate armorstands, or any cleanup if you remove the plugin)

Currently the only way to do this is via NMS, so a Player#sendEntitySpawn and a Player#sendEntityDespawn would be a useful method