According to the Oculus blog, talking to Messenger friends through your headset does not affect your Oculus privacy settings. You can still use Oculus Chats to send friends with your Oculus username as well. Facebook unveiled in the fall that it would bring Messenger to Oculus, not long after announcing that all Oculus headsets will eventually require a Facebook account to use.
Software update v25, which is gradually underway, also offers a feature called App Lab. It provides developers with a way to distribute their apps and games outside of the Oculus Store without users having to download them. Facebook suggests that it can maintain high quality in-store, while providing developers with a safe, secure way to share creations that can be more refined or experimental.
Although these apps may not be in the Oculus Store, you can still search for them if you know the exact name, and it will appear in the App Lab section of the results. Developers can also share their apps with a URL. Any App Lab games or apps you purchase will be added to your Quest library and they will receive automatic updates.