So they write a bunch of drivers and stuff for pine phone. As a pine fan I thank them, but this doesn't mean we can't have a difference in opinion what does it mean for some component to be a black box.

If you compare with some other manufacturer that gives us absolutely no docs, then yes having register level docs and user side source is really nice. But if you want to do something unconventional (like switch the whole damn thing off and bypass its latency) not knowing how it works internally is still a black box. For example there is an irq that fires when the first component of the isp(MI-memory interface) sees a vsync signal for a frame. We know it exists. We know how to enable/disable that irq. We can write code that does stuff when it fires. But what we don't know is is this vsync signal fired truly at the input of the ISP? It's output? Or perhaps between some specific components? It turns out that vsync fires not when the isp sees the very first vsync what the location of the registers suggests, but after all the processing is done at the output buffer (40ms later usually), but one wouldn't be able to tell without a lot of profiling. This amongst other things is what I call a black box.

However, compare it with let's say a raspberry pi, and at register level the documentation is much better (for the isp).