is there any way to check if currently the device has airplane mode turned on through ADB?

You can try to execute those new commands (without requiring root permissions):

• If you want to know if the airplane mode is enabled or disabled:

  adb shell cmd connectivity airplane-mode

• If you want to enable the airplane mode:

  adb shell cmd connectivity airplane-mode enable

• If you want to disable the airplane mode:

  adb shell cmd connectivity airplane-mode disable