BTW -- does the Wikidata SPARQL endpoint currently
support CONSTRUCT and
DESCRIBE queries? I ask because you can use that as one of the many
options for dump production.
Yes, such queries are supported, but using this for dump production is
both not possible - since dumps are what the data in SPARQL service is
loaded from - and very inefficient, we don't really need SPARQL server
for that, it can be done with much simpler code.