dnf history undo versus GRUB kernel fallback for config preservation after a failed upgrade

Goal is to recover a Rocky Linux system after a failed upgrade while keeping service configuration consistent and avoiding manual drift.

The documented recovery options are dnf history undo, which reverts package transactions, and GRUB kernel fallback, which allows booting a previously installed kernel without reverting packages. dnf history undo is known to revert installed packages but does not automatically restore configuration files that were removed or altered during the upgrade, and may leave orphaned systemd units or services in a changed state. GRUB fallback preserves the upgraded package set and any configuration changes made by the upgrade, relying on the older kernel for bootability.

With Rocky Linux 9.x and dnf 4.x assumptions, the unresolved decision is how configuration file and systemd unit state should be treated when choosing between package rollback and kernel fallback.

Does dnf history undo restore configuration files removed during the upgrade transaction? What is the documented interaction between GRUB kernel fallback and upgraded services and unit files? Is there a documented policy for reconciling configuration drift when package rollback and kernel fallback are considered together?