Gregory's Server
DOI='10.1145/3356903'
curl "https://api.crossref.org/works/${DOI}" \
| jq -r '.message.abstract' \
| { \
echo '<article xmlns:mml="http://www.w3.org/1998/Math/MathML" dtd-version="1.2"><body>'
cat
echo '</body></article>'
} \
| pandoc --from jats --to commonmark
# Given DOI, get the article abstract (if it is available)
https://api.semanticscholar.org/ is easier for this purpose: https://api.semanticscholar.org/graph/v1/paper/10.1002/pds.5070?fields=title,abstract
But where's the fun in that! Also, it doesn't include all abstracts, although it has some that CrossRef doesn't (e. g. some medical ones, which they probably get from PubMed)