Java 关闭应用程序时单击通知按钮打开活动

I found it! See this answer.
This answer suggests enabling ScreeanOverlay settings because as of Android 10 and later you can no longer open an activity from the background just by calling the lines I've used.
To make it work, you'd have to add this permission through your Manifest.xml:

<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>

And then the user would have to enable the Display over other apps setting.
I searched for an option to get the user to this setting more easily and found this answer.
This answer gives a code that redirects the user to the Display over other apps setting

if (!Settings.canDrawOverlays(this)) {
    Intent intent = new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION, Uri.parse("package:" + getPackageName()));
    startActivityForResult(intent, 0);
}

and then I guide the user with the notification's content (text) on how to enable the setting.
Once the setting is enabled, The lines I've used before work.\

问题解决了吗？

还没有完全解决

this whole configuration described above works, but only if the app is not killed.
If the app was killed and I try the method listed above, the app joins the recent apps list, but won't open and show up.
A solution that solves this issue as well will be accepted as an answer instead of this one.