Support

Joomla! only allows us to display custom actions using plugins in the quickicon group.

Adding icons to the header doesn't work very well and breaks every few versions of Joomla due to small changes in the backend template (that was indeed the very first approach I tried back in late 2017, when I was working with Joomla 4.0.0-Alpha2).

The home dashboard is just modules. You can of course move the modules around to customise the display as you want. My wife had written a Joomla Community Magazine article about customising the backend: https://magazine.joomla.org/all-issues/february-2022/joomla-4-for-clients-part-2-creating-a-custom-admin-experience#admin-menus. Between admin menus and control panels you can design an interface that is just right for your clients. BTW, Akeeba Backup does offer admin menu items, including a menu item to start a backup — created at the insistence of my wife who needed this for her clients :)

Regarding the toolbar, I am never going to add anything there. It should only be populated by the current component. There's a lot of margin for screwing something spectacularly if we start messing around with the toolbar object without knowing what the current component's view is intending to do with it.

Regarding alerts etc, no, not directly. You can, however, create a new admin module of the Custom HTML type and place it at the very top of the Control Panel page. In there you can have any content you want, including the fact that the client needs to take a backup. You can of course do template overrides in the backend if you want to add messages, popups etc in select backend pages but this is more involved.

So, really, it's how much effort you want to expend beating into your client's head that they need to take backups more than what is technically feasible.