It is possible to Twitch stream from a Raspberry Pi 3B+, but it may not be the most ideal option. The Raspberry Pi 3B+ has a relatively low-powered processor and limited RAM, which can make it challenging to stream high-quality video without experiencing performance issues.
To stream on Twitch from a Raspberry Pi 3B+, you would need to use a program such as OBS Studio or Streamlabs OBS, which are available for Linux. You would also need to use a capture card or USB video capture device to capture the video output from your gaming device, since the Raspberry Pi does not have a built-in HDMI input.
Once you have set up OBS and your capture device, you can configure your stream settings, including the video resolution, frame rate, and bitrate. You can then start streaming to Twitch by entering your Twitch stream key into the OBS settings.
Keep in mind that streaming from a Raspberry Pi 3B+ may not be the most optimal solution, and you may experience performance issues or limitations with video quality. It is recommended to use a more powerful computer or console if you want to stream high-quality video content to Twitch.