>> Maybe just set window-start to the first non-empty line initially,
>> thus moving the empty line out of screen?
>
> Thought about this too. Could work, but the fact that it's not easy to
> "undo" the view if you pressed 'C-p' accidentally is a downside.

"undo" is a minuscule issue, or rather a non-issue at all,
whereas the idea is good.  Created a feature request bug#35860

>>> If you really must have it this way, do we have an example of invisible
>>> text expanding when cursor moves inside, and then contracting when it's out
>>> again? Meaning if would look like an empty line you wanted after you press
>>> 'C-p', but not visible at all otherwise.
>>
>> Yes, this is possible:
>
> It almost works fine, but going from the second log entry to the first with
> 'p' while at bol leads to the first (empty) line becoming visible.

Asked about this in http://lists.gnu.org/archive/html/emacs-devel/2019-05/msg00827.html
and the answer was to use reveal-mode.

> BTW, if we implement this, here's something we could add as well:
>
> Instead of the empty line, how about it will contain some quick help string
> for the 'd' command, so that the user is not too puzzled if they hit 'C-p'
> by accident?

Good idea, added too: