해결 방법

override fun onCreate(savedInstanceState: Bundle?) {
     super.onCreate(savedInstanceState)
     try {
         setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT)
     } catch (ignore: IllegalStateException) {}
 }

이렇게 해도 익셉션만 먹는거라 세로모드 고정 됨.

투명 액티비티 만들기

themes.xml

<style name="Theme.AppCompat.Transparent.NoActionBar.Dimmed" parent="Theme.AppCompat.Light.NoActionBar">
    <item name="android:windowBackground">@android:color/transparent</item>
    <item name="android:windowContentOverlay">@null</item>
    <item name="android:windowNoTitle">true</item>
    <item name="android:windowIsFloating">true</item>
    <item name="android:backgroundDimEnabled">true</item>
    <item name="android:windowIsTranslucent">true</item>
</style>

manifest.xml

<activity
        android:name=".ui.MainActivity"
        android:configChanges="uiMode"
        android:exported="false"
        android:theme="@style/Theme.AppCompat.Transparent.NoActionBar.Dimmed" />