Running LaunchDaemon immediately after macOS upgrade

New Contributor

I am trying to trigger an action to run immediately after the upgrade to macOS Catalina is complete (specifically, I need to trigger a recon so that Jamf Pro picks up the new OS version and deploys the appropriate configuration profiles).
I'm following the methodology of and creating a self-deleting LaunchDaemon. However, I can't get it to run immediately after the upgrade.
- The LD itself works correctly. If I reboot manually, whether before or after the upgrade, the recon gets run, and the LD deletes itself
- The command I am running to do the upgrade is

/Applications/Install macOS --rebootdelay 30 --agreetolicense --forcequitapps &

- This is on a device running 10.13.6 (mainly testing on a VM, but I've tried a physical device as well with the same effect).
- I have tried chaining the above command using &&, to either reboot, or manually load the LD afterwards, but this doesn't seem to make any difference.
- I have tried running the command directly, and from a script (with either the command itself as above, or wrapped in a script command to log to a file - in which case the log file is no longer present after the OS upgrade).

I'm tearing my hair out over this one. Anyone got any suggestions as to what I might be doing wrong, or how I can get the LD to run?