does someone happen to know if there is a ready tool to convert W3C EBNF declarations to format which instaparse understands?

specifically I’m looking for SPARQL ebnf declarations which I could feed into instaparse

I would also accept an ANTLR -> instaparse converter

instaparse understands the SPARQL grammar from w3c. you just have to adapt the production rules for the terminals so that instaparse will detect them as regexes. See for instance https://github.com/mladvladimir/sparqlom/blob/master/resources/sparql.ebnf