Unfortunately there is no option to browse other lobbies or to join a random one, you can only host a lobby and invite your friends or join a friend's lobby.

Random Matchmaking Coming Soon

Per developers new video [https://youtu.be/A3k0qj6J1yY?si=yDdM0DqAr88Q8trG] joining random people coming soon.

Steam

1. Open Steam app and go to Discussions of R.E.P.O. [https://steamcommunity.com/app/3241660/discussions/]

2. Look for lobbies or invite people to your lobby by Starting a New Discussion.