How can I attach to a remote debug server without a PID or program name?

For example, debugging something on an iOS device from a laptop. When debugging an iOS process remotely with lldb, a debugserver instance runs on the remote host. debugserver is given a program to launch or a process to attach to, so the local lldb instance doesn't need any of this information. I've looked at Pipe Transport and it requires a PID. I see there is a command:pickRemoteProcess option, but where do I supply a way to start the remote server? Perhaps something with setupCommands?

Under the hood, Xcode communicates with the device and launches an instance of debugserver, supplying a port. If you're not familiar, the workflow by hand is something like this. On the remote host:

$ debugserver --attach=$pidOrProcessName *:12345
  Waiting for connection from *:12345...

On the local host:

$ lldb
(lldb) platform select remote-ios
(lldb) platform connect connect://$deviceIP:12345
<debugging starts>

Is this a supported configuration?

Review Documentation/Debugger/gdb/PipeTransport.md and the handling of command:pickRemoteProcess and setupCommands. Trace how remote debug-server startup is represented for the iOS workflow; done means determining and documenting a supported configuration or identifying the missing integration.