How can I check the battery level of my Bluetooth connected phone in the standalone smartwatch app or watchface?

I try to find a way to get the phone's battery level from a watch wearable device. Is there any way to get it from the standalone watch app? Of course, it has a Bluetooth connection.

I want to know about 2 cases.

1. Phone: Android, Smart Watch: Android native wear 2.0 (kotlin or java)
2. Phone: Android, Smart Watch: Tizen Web App (javascript)

In neither case (Tizen nor Wear OS) is it possible to get phone battery information in the standalone watch app. You'll need to build a companion phone app and send this data yourself.