launchd residual-process-group cleanup after main-job death: supported signals and timing

For current macOS 27, I am trying to establish the supported behavior of residual process-group cleanup before selecting an architecture.

Consider a per-user launchd job whose actual main process O directly creates one fixed child F. F remains in the job's process group, creates no descendants, and does not change its process group or session. AbandonProcessGroup is not enabled. O may exit normally, crash, or receive SIGKILL while F remains alive. This is a documentary question; I am not presenting runtime observations or a reproducer.

The installed launchd.plist(5) manual (dated 30 July 2019) describes cleanup of remaining same-process-group members when a job dies. It describes ExitTimeOut in terms of stopping a job. Historical Apple source contains a SIGTERM attempt in job_reap, but I do not assume that code describes current macOS behavior:
https://github.com/apple-oss-distributions/launchd/blob/49a9c79b2949192dfca697b1054245cdfb645788/src/core.c

1. What signals and escalation, if any, are supported for F after O has already died? Does the answer differ for normal exit, crash, or SIGKILL, or by per-user job domain?
2. Does ExitTimeOut apply to that residual group after O is dead, or only to stopping the main job process?
3. Is there a supported finite upper bound from O permanently ceasing execution to F being unable to execute further, including stopped or blocked F and O dying during child creation? If so, what is its documented timing origin and treatment of system sleep? If there is no supported bound, that clarification is sufficient.

I have read the DTS answer about job runtime and CPU-versus-wall-time limits:
https://developer.apple.com/forums/thread/845944
My question concerns residual-group cleanup after the actual main job process dies, rather than a separate requester's disappearance or the runtime limit of a still-live job.