Hi and thanks for your quick response.
Just to double-check - I don't think the page you've linked contains an answer to the question "is a devlog of a draft game visible?". I take your word for it, of course - just letting you know in case the answer was supposed to be there.
One thing I found that seems remotely connected to the subject:
Although, if you create devlog entries, then those will be indexed if the page is public.
But it doesn't clarify if they will be indexed if the page is not public. I know I can just go ahead and try but I wouldn't want the attempt to count against "Don’t try to circumvent any indexing restrictions" in case anything goes wrong.
Thanks.