Currently if you change an entity icon, it overrides the default icons set for different states, with just one icon. The only option to customise the whole set of icons is to use built in device classes. But that’s very limiting.
I suggest we add more customisation options. This could be done on different ways, but the ultimate scope for me would be this:
UI for the basic states, that is ability to adjust any icon that currently is different in different devices classes. For example covers have different icons for open, opening, closing and closed.
Support for templating, when used it overrides the above, and then we can make the icon depend on anything we want.