In this guide I will show you the 7 shop locations currently available to my knowledge:

1/ Popop ShopShop
If you have already launched the game and finished the tutorial, you can't miss it!

2/ Island Plot Shop
For this one you simply need to head towards the beach to find a large tower on an island and right next to it you will find the location of the shop

3/ The HillsideShopPlot
To find it, simply leave the McQuillan ranch and follow the road on the right

4/ Dojo Shop Plot
To find it you will have to explore a little, it is located on a hill to the north of the map near Kazai Castle

5/ Smithrock Shop Plot
A somewhat unusual shop which is located at the top of a mountain to access it you will either have to find the zip line that goes up there or do the Aiden quest to obtain the glider (I will explain it in a future guide)

6/ Southern Snow Shop
To find it you will have to explore north of Snowville it is located on the edge of a mountain on the right

7/ Snow Shop
As for 5, it is located around Snowville not far from shop 5, you just have to continue north.

Don't hesitate to comment if you have any questions. Thank you for reading this guide!