Thanks once again, Quinn!
To close the loop: I ended up transforming the LaunchAgent into a regular application with a Dock tile to prevent it from being killed outright during the logout orchestration. I even found some useful operations to be exposed via the tile, so it's not just a dummy UI. My upstream fixes to Home Assistant OS to speed up shutdown (https://github.com/home-assistant/supervisor/pull/7448) were also merged, so that the next release has higher chances of fitting into the 60 second budget. Until the man page is updated, this forum post serves as documentation for the ExitTimeout cap.
Topic:
App & System Services
SubTopic:
Processes & Concurrency
Tags: