https://wccftech.com/steam-chat-now-available-on-android-and-ios/

A mobile version of Steam has been around for a long time. The app gave you a truncated Steam experience but was missing key features such as Chat. Today, Valve announced that the new Steam Chat mobile app has gone live as a free chat app iOS and Android platforms. The app includes many key features of the Steam Client desktop chat, including:

You can get the app on the Apple App Store and the Google Play Store using the included links. The app is still relatively new and Valve wants your feedback on it. A future version of the app may include voice as well, according to Valve. With Steam Chat moving to its own dedicated app, the original Steam Mobile app will see significant upgrades focused on account security such as better Steam Guard options QR codes and one-touch login, and improved app navigation.