Force resign the first responder in SwiftUI

Question

I currently use a QLPreviewController in a SwiftUI app with the help of UIViewControllerRepresentable to display a PDF.

This works well as the user can interact with the PDF using the keyboard to input data but also using PencilKit

I was wondering if there was a way to force resign the first responder within the QLPreviewController as the input could either be a text field with the keyboard or drawing with the PKToolPicker.

This is what I tried:

1. I created this extension to find the key window based on this answer

extension UIApplication {
    
    var keyWindow: UIWindow? {
        // Get connected scenes
        return self.connectedScenes
            // Keep only active scenes, onscreen and visible to the user
            .filter { $0.activationState == .foregroundActive }
            // Keep only the first `UIWindowScene`
            .first(where: { $0 is UIWindowScene })
            // Get its associated windows
            .flatMap({ $0 as? UIWindowScene })?.windows
            // Finally, keep only the key window
            .first(where: \.isKeyWindow)
    }
    
}

2. Then using this answer, I execute this line of code when tapping on a SwiftUI button:

UIApplication.shared.keyWindow?.endEditing(true)

However this doesn't seem to dismiss the keyboard nor the PKToolPicker

3. I've even tried the below which I found on another answer:

extension UIApplication {
    func endEditing() {
        sendAction(#selector(UIResponder.resignFirstResponder),
                   to: nil,
                   from: nil,
                   for: nil)
    }
}

And while this worked when on my login form when I wanted to dismiss the keyboard, this doesn't seem to work within the QLPreviewController

Is there any other way I can force resignFirstResponder or is there something similar to end editing for SwiftUI ?