How to structure a database in firestore

I am creating an application related to pets, so I am in confusing with create the structure of database...

For example I have the below categories:

1. Pets
2. Pets accessories
3. Pets food

for categories each one have a name and an image

and for each category have sub categories like the below one for example I'll call it as products:

 1. image: ""
    name: Hulk
    type: Pets
    age: 2
    price: 200

 2. image: ""
    name: bowl
    type: Pets accessories
    price: 20

 3. image: ""
    name: Gosera Cat
    type: Pets food
    price: 15

I am sorry if it is basic question or something, but I just want to know what is the best way to create a database structure in fire store like the previous one...

#Edited I tired to create the categories something the below image:

any suggestions or advice?