Would it be possible to add a bee model NPC?

Mhhh you could already do this with some limitation over the new custom models like:

I've used the render command to display an npc as a bee but having a bee be able to animate properly and hover (I don't know if that is even possible though)

Bro i don't see the Change model button why?

Are you on the latest version?
If not there's a command for it:
/easy_npc render set entity [UUID] [entity type]