Here is what I would like: I'm typing and I want to cite something. I press a key and I can search by author, title in a database of everything ever published. When I make my choice a cite key is inserted in my format of choice (Pandoc) and the bibliographic information is pulled from that big database to a local file. This file is kept in sync with the big database and my own document, until I decide to 'freeze' it and it becomes static as a permanent record.
Maybe what I want would actually be bad because it assumes that I'm on the internet whenever I write, and doesn't involve a local database of PDFs.
IIRC, ReadCube (https://www.readcube.com/) organizes and extracts metadata of local PDFs and can also search across different search engines to download and extract metadata from online articles.
Not sure how that compares to Zotero, but ReadCube was definitely helpful for me when I was involved in research.
(note: subscription required; offers 30-day trial)