How do I pass a value from a Child view across multiple views in SwiftUI?

In my project, I need an id of a 'Product' to be printed to the console when I tap a button. I am accessing an 'id' of a product in one of my child views and printing it to the console (when it is tapped within a child view). I need to use this id in a button in a different view. How do I do this? Here is the structure of the views:

struct IntroView: View {
var body: some View {
VStack {
CustomSelectView()
Button("Continue") {
//Here is where the 'selectedProduct' data in ProductRowViewOnboard() needs to be accessed
}
}
}
}
struct CustomSelectView: View {
@State private var showingProductSheet = false
var body: some View {
HStack {
VStack {
Text("Select Product 1")
}
.onTapGesture {
print("Select Product 1 Tapped...")
showingProductSheet.toggle()
}
.sheet(isPresented: $showingProductSheet) {
ProductSheetOnboard()
}
VStack {
Text("Select Product 2")
}
.onTapGesture {
print("Select Product 2 Tapped...")
showingProductSheet.toggle()
}
.sheet(isPresented: $showingProductSheet) {
ProductSheetOnboard()
}
}
}
}
struct ProductSheetOnboard: View {
@Environment(\.dismiss) var dismiss
@StateObject var marketplaceModel = MarketplaceViewModel()
let product_id: String
var body: some View {
var columns = Array(repeating: GridItem(.flexible()), count: 2)
let defaults = UserDefaults.standard
let keyString = defaults.string(forKey: "key") ?? ""
ScrollView(.vertical, showsIndicators: false) {
VStack {
ForEach(marketplaceModel.filteredProduct, id:\.self){ product in
ProductRowViewOnboard(productData: product,  product_id: product_id ?? "")
}
}
}
.onAppear {
let defaults = UserDefaults.standard
let keyString = defaults.string(forKey: "key") ?? ""
self.marketplaceModel.fetchProductTags(key: keyString ?? "")
self.marketplaceModel.fetchMarketProducts(key: keyString ?? "")
}
}
}
struct ProductRowViewOnboard: View {
@Environment(\.dismiss) var dismiss
@State var selectedProduct : ProductTile?
var productData: ProductRow
let product_id: String
var body: some View {
HStack {
ScrollView {
HStack {
ForEach(productData.products ?? []) { product in
ProductView(productData: product)
.onTapGesture {
selectedProduct = product
//The following print statement works 
print("Product id: \(selectedProduct?.id ?? "")")
let defaults = UserDefaults.standard
let keyString: String? = defaults.string(forKey: "key") ?? ""
// The data in selectedProduct here needs to be accessed in IntroView()
}
}
}
}
}
}
}

In the last view I provided (ProductRowViewOnboard) in the .onTapGesture{}, I have accused the id of the product. I need to access this value in IntroView() so I can use it in the Button.

I can't seem to do it.

You need to move the state up to where it is needed first and then pass down let for read access or @Binding var for read/write access, e.g.

struct IntroView: View {
@State var selectedProduct : ProductTile?
var body: some View {
... 
ProductRowViewOnboard(selectedProduct: $selectedProduct)
...
}
}
struct ProductRowViewOnboard: View {
@Binding var selectedProduct : ProductTile?
}

Also in SwiftUI, the View struct should be your primary encapsulation of view data. Don't use view model objects because you'll have trouble getting other view data in and out of them (as you have probably experienced by your non-standard use of onAppear); you'll also get consistency bugs which SwiftUI's use of value types for the View struct is designed to eliminate.