PreviewOneModelView.swift

import SwiftUI
import SwiftData

struct PreviewOneModelView<Model: PersistentModel, Content: View>: View {
  var content: (Model) -> Content

  var body: some View {
    PreviewOneModelContent(content: content)
      .modelContainer(for: Item.self)
      //.modelContainer(for: [Item.self], inMemory: false) // OK
  }
}

struct PreviewOneModelContent<Model: PersistentModel, Content: View>: View {
  var content: (Model) -> Content
  @Query private var models: [Model]

  var body: some View {
    content(models.first!)
  }
}