If you want to run HTML games (or any html file) on Android 11, expect some trouble, google has restricted navigator access to multimedia files only. I managed to find a way, so I might as well share it. Works with Chrome, haven't tested other navigators but I guess it's similar.
1. Plug your phone to a computer, there is some hidden folders you can't access throught your phone since android 11.
2. Navigate to /Android/data/com.android.chrome/files/Download/ and paste your game/file here.
3. On your phone's chrome, input file:///storage/emulated/0/Android/data/com.android.chrome/files/Download/game_folder/game.html (replace game_folder/game.html obviously, and I don't know if it works on sdcard). You may have to manually input it as you can't navigate to it and copy the file path, so make sure there is no mistake in the path.
Enjoy
1. Plug your phone to a computer, there is some hidden folders you can't access throught your phone since android 11.
2. Navigate to /Android/data/com.android.chrome/files/Download/ and paste your game/file here.
3. On your phone's chrome, input file:///storage/emulated/0/Android/data/com.android.chrome/files/Download/game_folder/game.html (replace game_folder/game.html obviously, and I don't know if it works on sdcard). You may have to manually input it as you can't navigate to it and copy the file path, so make sure there is no mistake in the path.
Enjoy