I'll note that the question was changed (not by the OP) to focus on books. I'll answer that first.
I think it is unlikely that publishers, often represented by senior (acquisitions) editors, to solicit books from students, but very common for them to talk to professors about book ideas. In some cases, the professors might send them to students who have some interesting work. Some of my books were solicited, but I'd established a reputation by then.
Book chapters are a bit different. Beware that some predatory publishers are on the prowl among the unsophisticated to get materials for less-than-reputable publications, but really good publishers will do this also.
In my opinion (note: opinion), the best such books have been suggested by some senior researcher who has some, but not enough, material for a book and has convinced a good publisher to help put it together, perhaps by going on the prowl for submissions. But here, the senior researcher, not just an editor has some control over the book, which should guarantee both success and quality. In such a book, the sponsoring professor or researcher will probably write the introduction and have one or more of the major contributions. The contributions may all be recent or the intent may be to bring an historical consolidation of some topic.
Other meetings of publishers and doctoral students are more likely to be just informational, with no commitments being made. The publisher is saying "We Exist - consider us for your next paper". The discussions will be informational in nature, mostly: This is what we want to print (or not). But you wouldn't' get any commitment to publish even a completed paper at a conference if the journal has any credibility. The paper will still need to be reviewed by subject matter experts with an eye to improvement.
That said, it is good to establish such relationships with journals, even if they are very tentative.