As Session is a project of the Oxen Privacy Tech Foundation, court orders in situations such as this would be targeted at the Foundation.
The OPTF can be forced to comply with lawful court orders, but compared to most messaging apps, this would still yield very little information. The OPTF could not reveal user identities; the Foundation simply does not have access to the data required to do so. Session ID creation does not use or require email addresses or phone numbers. Session IDs (which are public keys) are recorded, but there is no link between a public key and a person’s real identity, and due to Session’s decentralised network, there’s also no way to link a Session ID to a specific IP address.
The most the OPTF could provide, if compelled to do so, would be information such as access logs for the Session website or statistics collected by the Apple App Store or Google Play Store.