yep — or just make a new image with FROM and the stuff copied into it as a new layer; and push it to your registry, and get the benefits of layer caching etc in your CI etc.
The problem isn’t that you can’t do things like that though… it’s just that preparing that layer is work, and it’s also work you need to repeat to get any updates. At some point you want a maintained CI process behind that; which is really what the convenience images give you.
Mm, that's why I like the approach of only maintaining the top extra patch layer - you still get to use the maintained layers below it