Telegram might support RTMP Live Broadcasts
A mention of RTMP Live Broadcasts appeared in Telegram API schema.
This will let streamers broadcast not just using the Telegram app, but also using third party software, e.g. OBS Studio. Such software allows composite video and audio from different sources, automating the broadcast, displaying chat and donations. RTMP is a common standard and is supported by other live broadcasting platforms like YouTube and Twitch.
Currently to make a live broadcast backed by third party software you need to use libraries, or you can use OBS by its emulated camera feature passed through Telegram Desktop or Telegram for macOS.