Determining/associating the log subsystem for apps installed via package managers
The subject here are the configuration files for Apple's Unified Logging system - in particular for subsystems.
Yes, the subsystem is something the developer can specify in their code. A developer that uses Unified Logging on macOS commonly do so by calling into the OSLog class on macOS 10.x, or the Logger class on macOS 11.x. When initialising an instance of the class, the developer can provide the subsystem as a string - which is recommended to be in the reverse DNS notation (i.e. com.openssh.sshd for example).
The developer is free to create multiple subsystems for various parts of the program, so you could in theory have &quot;com.openssh.sshd.authentication&quot; and &quot;com.openssh.sshd.network&quot; subsystems.
The developer can also choose not to specify a subsystem at all - and just log something. This is typically what happens with developers that did not take Unified Logging into account. In that case macOS supplies a default subsystem name - in general this is the bundle identifier for the app.