How to refactor native Android Java method to be called from React Native?

I currently have the following activity which is created when my app starts and is declared as an activity in my AndroidManifest.xml:

AndroidManifest.xml:

<activity android:name=".IncomingActivity"></activity>

IncomingActivity.java:

package com.xyz;

import android.os.Build;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.WindowManager;

public class IncomingActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O_MR1) {
            setShowWhenLocked(true);
            setTurnScreenOn(true);
        }
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN | WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON
                | WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON | WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED
                | WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD);

        setContentView(R.layout.activity_incoming);
    }
}

I now want to be able to use this functionality on demand from React Native. I have refactored it like the below so far but when this native method is called, I just get a blank white screen and I think the problem is this line: activity.setContentView(mReactRootView);

Updated class:

public class UnlockDevice extends ReactContextBaseJavaModule {

    @Override
    public String getName() {
        return "UnlockDevice";
    }

        private ReactContext mReactContext;
        private ReactRootView mReactRootView;

    public UnlockDevice(ReactApplicationContext reactContext) {
        super(reactContext);
                mReactContext = reactContext;
                mReactRootView = new ReactRootView(reactContext);
    }

    /* React Methods */
   @ReactMethod
    public void Unlock() {
                    Activity activity = mReactContext.getCurrentActivity();

                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O_MR1) {
                    activity.setShowWhenLocked(true);
                    activity.setTurnScreenOn(true);
                }
                
                activity.getWindow().addFlags(
                        WindowManager.LayoutParams.FLAG_FULLSCREEN 
                        | WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON
                        | WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON 
                        | WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED
                        | WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD);

                activity.setContentView(mReactRootView);
    }
}

What is the correct way to be able to call this method to toggle the functionality but with the main activity instead of starting a new one?

from How to refactor native Android Java method to be called from React Native?