I second this answer; using this approach myself for a couple of years now. Works almost always except there are updates for NVIDIA drivers, for which I've created an issue upstream at https://github.com/PackageKit/PackageKit/issues/554

On Fri, Jun 30, 2023 at 2:06 PM Andrei Borzenkov <arvidjaar@gmail.com> wrote:
On 30.06.2023 13:46, Daniele Granata wrote:
> Dears,
> in recent months make a zypper dup cause some problems to my system,
> logout from kde broken, session that will not close properly keeping
> open sw like Chromium or DBeaver, all resolved with a hard power off.
> May I ask some sort of option in zypper dup to apply the file
> installation only before the next boot?
>

a) Install discover-notifier and enable offline updates in system settings

b)

pkcon update --only-download
pkcon offline-trigger
systemctl reboot


--
Regards,
Andrei Dziahel