Is there a database of publications for nearly all major disciplines?
LENS.org offers a free API comprising data from ca. 224 million scholarly work (according to that page about the API).
In comparison, CrossRef has ca. 120 million records (source), also with an API.
But note that the metadata from both LENS and CrossRef are limited. For instance, they do not track self-cites, they do not analyse author collaboration networks, they do not generate author profiles through algorithms (though LENS seems to plan doing so with the help of ORCiD). For such advanced purposes, commercial databases such as Web of Science, Scopus, or Dimensions are the go-to platforms.