Once you have a DOI (from crossref or otherwise) you can get a legal download link simply by putting 'https://doi.org/' in front of it (though it will often go to a summary/login page rather than the PDF) and a SciHub PDF link by prepending 'https://sci-hub.ru/'. Or am I missing something?
I already use scihub (I explained in the post). However, it is much much slower than google scholar.
It seems to me that Crossref can give you the DOI, and once you've got that then getting to article text is pretty trivial. I must be missing something.
Google blocks you once you use python to request it multiple times (I explained in the post).
Ah sorry. I guess I don't understand what you are looking for.