Thanks a lot for the detailed response! I was indeed not aware of the scope of the problem and the fact that it has its own Wikipedia page.

Also many thanks making me aware of ORCID (together with "DamonHD"). After doing some digging I found ORCID API endpoints which are able to resolve DOIs and PMIDs to ORCID profiles, which is great.

I will take a closer look at the "disambiguation" project you linked to and will see what approach I can take for reliably resolving email addresses to first names (while filtering out non-personal email addresses).

That being said, I fear that resolving non-ORCID + non-email authors using the SerpApi + LLM approach I described in my initial post is still the best shot I currently have.