they are not mutually exclusive. nature allows for preprints on arxiv according to wikipedia.

also deepmind published in nature justthis month.

Everything? They publish basically extended abstracts, nothing that could be confidently reproduced, nor code ... or I just don't know how to read it and find supplemental material. There's a lot in the bibliography. Really just a journal article, an entry in a log book.

but they also seek publications in the main Nature, which is unusual in the field.