I hate quaternions

Is there a way to transform normal rotation (x & y) into quaternions?  Im making a datapack that adds functional cars to Minecraft, and i need to use item displays for the car bc if i use armor stands the car will stop being rendered unless youre looking at the center of the car. The thing is that for some reason mojang decided to use quaternions as the rotation method for entity_displays so idk how to rotate my model