android mobile demo mode. From https://awenger.de/android/2020/05/26/clean-android-screenshot-and-screen-recording.html

adb_presentation_end.sh

adb shell am broadcast -a com.android.systemui.demo -e command exit

adb_presentation_start.sh

adb shell settings put global sysui_demo_allowed 1
adb shell am broadcast -a com.android.systemui.demo -e command enter
adb shell am broadcast -a com.android.systemui.demo -e command clock -e hhmm 1000
adb shell am broadcast -a com.android.systemui.demo -e command battery -e plugged false
adb shell am broadcast -a com.android.systemui.demo -e command battery -e level 100
adb shell am broadcast -a com.android.systemui.demo -e command network -e wifi show
adb shell am broadcast -a com.android.systemui.demo -e command network -e wifi show -e level 4
adb shell am broadcast -a com.android.systemui.demo -e command notifications -e visible false

adb_screenrecord.sh

#TARGET_DIR="$HOME/Pictures/adb-screenshots/"
TARGET_DIR = "./" #current folder
FILE_NAME="$(date +"%Y-%m-%d-%H_%M_%S").mp4"
SCRIPTS_DIR=$(dirname $0) 

function fetch_video()
{
  echo "retrieving file"
  sleep 1
  mkdir -p $TARGET_DIR
  adb pull /sdcard/$FILE_NAME $TARGET_DIR$FILE_NAME
  adb shell rm /sdcard/$FILE_NAME

  $SCRIPTS_DIR/adb_presentation_end.sh
  echo ""
  echo "File: $TARGET_DIR$FILE_NAME"
  xdg-open $TARGET_DIR$FILE_NAME & disown
}

echo "waiting for device..."
adb wait-for-device

$SCRIPTS_DIR/adb_presentation_start.sh

echo "ctrl+c to stop recording"
trap fetch_video SIGINT
adb shell screenrecord /sdcard/$FILE_NAME

adb_screenshot.sh

#TARGET_DIR="$HOME/Pictures/adb-screenshots/"
TARGET_DIR = "./" #current folder
FILE_NAME="$(date +"%Y-%m-%d-%H_%M_%S").png"
SCRIPTS_DIR=$(dirname $0)

echo "waiting for device..."
adb wait-for-device

$SCRIPTS_DIR/adb_presentation_start.sh

mkdir -p $TARGET_DIR
adb exec-out screencap -p > $TARGET_DIR$FILE_NAME

$SCRIPTS_DIR/adb_presentation_end.sh

echo ""
echo "File: $TARGET_DIR$FILE_NAME"
xdg-open $TARGET_DIR$FILE_NAME & disown

adb_screenshot_only.bat

:: for windows

SET "TARGET_DIR=%~dp0"
SET "FILE_NAME=%date:~0,4%-%date:~5,2%-%date:~8,2%-%time:~0,2%_%time:~3,2%_%time:~6,2%.png"
SET "SCRIPTS_DIR=%~dp0"
ECHO waiting for device...
adb wait-for-device
::mkdir "%TARGET_DIR%"
adb exec-out screencap -p > "%TARGET_DIR%%FILE_NAME%"
ECHO.
ECHO File: "%TARGET_DIR%%FILE_NAME%"
start "" "%TARGET_DIR%%FILE_NAME%"

adb_screenshot_only.sh

#TARGET_DIR="$HOME/Pictures/adb-screenshots/"

TARGET_DIR="$(dirname $0)/"

FILE_NAME="$(date +"%Y-%m-%d-%H_%M_%S").png"
SCRIPTS_DIR=$(dirname $0)



echo "waiting for device..."
adb wait-for-device



mkdir -p $TARGET_DIR
adb exec-out screencap -p > $TARGET_DIR$FILE_NAME



echo ""
echo "File: $TARGET_DIR$FILE_NAME"
xdg-open "$TARGET_DIR$FILE_NAME" & disown

switch system language by adb.txt

At first, install "settings_apk-debug.apk" from https://github.com/appium/io.appium.settings

then:
adb shell pm grant io.appium.settings android.permission.CHANGE_CONFIGURATION


#en
adb shell am broadcast -a io.appium.settings.locale -n io.appium.settings/.receivers.LocaleSettingReceiver --es lang en --es country US

#chinese
adb shell am broadcast -a io.appium.settings.locale -n io.appium.settings/.receivers.LocaleSettingReceiver --es lang zh --es country CN


Thanks to: https://julioevm.github.io/automation/appium/android/2021/02/25/android-locale.html