I just discovered a project called DIUN, which reports if there are pending updates to containers.
I always try to use containers provided by top level developers (when possible), like linuxserver. One of linuxserver's recommendations is always to update manually, not to use automatic updaters like Watchtower or others. The downside of this is that you have to be aware of whether the containers have updates.
Perhaps it would be possible to integrate DIUN as a service in OMV and in the notification system, so that you receive an email when there is a pending update of a container.
From what I see in the DIUN documentation it can be installed as a service using systemd on debian.
I am aware that what I propose is more work for ryecoaaron, and it is not the best time ...
Perhaps there is a simple way to implement this in the CLI for now, until OMV 6 is stable and there is less work to be done. I do not feel qualified to try. Is it possible for someone to clear the way a bit?
This application can also be installed on docker, if there is no other way it would be the solution. But I think it is cleaner to integrate it into the OMV notification system if possible.