Hii, I don't know entirely ! I am not a unity programmer myself but i think it is doable if you have the basics down and you are willing to learn, i have a gameplay reference for you to look at, i'm sure that will help to know better about the difficulty!
https://www.youtube.com/watch?v=5WiyPvm2YwU&ab_channel=GameSpotTrailers
for this game im making it would have. very similar to the video above me
- moving customers
- customer reactions
- score system
- hp system
- and key combination system , like a password structure for the orders inside the game
- timer systems for each customer. patience meter
- and some quick random dialogues after each order from time to time
- menu pop ups, like the food have to appear when you press a button and stuff
- randomized orders from customers
that's the things i can think of.