Yes, pretty amazing lack of documentation. I suspect some of this is because a) it is being shared by multiple functions, some of which did not exist previously (speech to text), it is showing information, not explaining functions (which are in other help sections), and c) the functions are still being worked on. But the basic information needs to be in the documentation.
Here's most of what I know....
It appears to me that many panels are addressed in general in terms of Panel behavior, but don't have their own page:
When it is "off," you can see the "Open Progress Dashboard" icon easily. When the dashboard is "on," the icon is almost invisible. But it is there. And even though its tooltip still says "Open Progress Dashboard," it will turn it off. You can also dismiss it with Escape. It does not appear to be dockable or resizable.
When "progress" occurs the icon changes to a broken circle. Upon completion, it changes briefly to a circle with a checkmark.
So if you don't want to dock the Progress panel or navigate to Window-> x to open it, you can click the Progress Dashboard icon.