Do Meta's Multiplayer services only provide invite multiplayer or is it more similar to steamworks

I am working on a peer-to-peer vr game and looking into multiple options for multiplayer. I know Steam has steamworks, which acts as multiplayer servers for Steam-only games. I was looking into various OnlineSubsystems (I am on unreal engine) and I found meta/facebook supposedly has one. It is hard to find documentation so I wanted to ask if the multiplayer services can be used for general multiplayer with strangers, rather than friended or party users.