@rochdale Welcome to the community.
You can have both businesses under the same Square account, but a Square POS is generally assigned to one location at a time. You can switch locations in the app, but it isn’t designed to operate as two locations simultaneously on one register.
Since your pizza trailer and ice cream stand are physically together, the simplest solution may be to set them up as one Square location and use separate categories, menus, websites, or reporting tags to distinguish pizza sales from ice cream sales.
Square does allow multiple Square Online websites under one account, and they can share the same item catalog while showing different items on each site. Online orders can then appear in Order Manager on the POS.
Here is the Square Documentation on managing multiple websites.
https://squareup.com/help/us/en/article/7088-manage-multiple-websites-with-square-online-store
