FHIR server implementation having a RDF triplestore

Dear community,
I am looking for a FHIR implementation (server) that stores the resources
in native RDF FHIR, so that I could do complex SPARQL queries on top of the
database, but also expose REST API endpoints in FHIR. (Not so much
interested in the U from CRUD, but at least Create, Read and Delete would
be enough)

For example what I would like to query on the FHIR store would be something
like:
* Retrieve all patients that are older than 18, not dead, having a body
weight bigger than 100kg and that have laboratory of insulin higher than
xyz .

Unfortunately I can only find FHIR server implementations with a RDBMS or
mongo as data storage . Do you know if some FHIR server implementations
exists with an RDF triplestore as data storage where the TTL of FHIR
resources would be stored natively?

Thanks for your help.