Even though Telegram's app lets you stream live events, it doesn't have a built-in way to stream content from other apps. On the other hand, Telegram live streaming is compatible with a wide range of apps.
You can use a screen recording app to capture the content you want to stream and then share the recording via Telegram's live streaming feature. There are many screen recording apps available for both iOS and Android.
Some broadcasting apps, such as Streamlabs or OBS, allow you to stream content directly to Telegram. You'll need to set up a custom streaming destination in the broadcasting app with your Telegram live streaming URL.
Some third-party services, such as Restream, allow you to stream content to multiple platforms at once, including Telegram. You can set up Restream to receive your content from a variety of sources and then forward it to Telegram's live streaming feature.
If you have development skills, you can create a custom solution to stream content to Telegram's live streaming feature. You'll need to use Telegram's Bot API to authenticate your app and send the stream to the appropriate chat.
In general, although there isn't a simple way to use Telegram live streaming with other apps, there are a few workarounds that can be used to get the job done.