Is there any workaround for the OAuth?

Essentially: no

In order to use the API requires an oAuth token.

The “fix” here is instead of the extension calling the API, is the extension calls your server, and your server says if the streamer is live or not.

Then your server can use eventsub instead for stream up/down notifications. So you don’t even have to call the API as Twitch will tell you when a stream is live or not.