Papers are always so careful to point to grant info (when applicable), so it always bothered me that they didn't have any dates in them. I've been a proponent of including a footnote or something that includes the research period, or date of first authorship, or something. I didn't gain much traction when I was in academia with this, since various publications have pretty strict formatting rules. You may be in a position to push on that idea though!
I've seen a lot of discussion on publication dates, drafts, acceptance, preprints, publication, revisions, etc. However this is the first time I've seen someone mention the research period. It's a fascinating idea. If you want to push this, perhaps an avenue might be to talk to crossref. While they're not the only DOI registration agency, they cover most western content and are good with their APIs. They regularly have events and meetups, and have always been good for a chat. https://www.crossref.org/events/
They're a (relatively) central point for this kind of metadata.
> You may be in a position to push on that idea though!
Ah, unfortunately probably not, I'm very much on the receiving end of the data.
> Papers are always so careful to point to grant info (when applicable),
There's a lot here - surprisingly common for this not to be the case! Funders definitely want this though.
