Primary Data Assets

You can create a UPrimaryDataAsset in C# using UCSPrimaryDataAsset.

[UClass]
public partial class UItemPrimaryDataAsset : UCSPrimaryDataAsset
{
    public UItemPrimaryDataAsset()
    {
        AssetName = "Item";
    }
    
    [UProperty(PropertyFlags.EditDefaultsOnly)]
    public partial FText ItemName { get; set; }
}

AssetName needs to match up with the type assigned in AssetManagersettings in your project settings.