Reading the documentation, it appears that the Session class only supports the beforeLogin and afterLogout triggers. Is there really no solution to execute operations after a session expires?
I was considering running a Job in the meantime, but I would need to execute it frequently to avoid missing the automatic database cleanup.
If no official solutions truly exist, I would suggest an afterExpiration trigger to perform tasks on sessions as soon as they expire. This would be very useful if sessions are also used to manage external services.