There are open source projects moving toward this scale, the GraphBLAS for example uses an algebraic formulation over compressed sparse matrix representations for graphs that is designed to be portable across many architectures, including cuda. It would be nice if companies like nivida could get more behind our efforts, as our main bottleneck is development hardware access.
To plug my project, I've wrapped the SuiteSparse GraphBLAS library in a postgres extension [1] that fluidly blends algebraic graph theory with the relational model, the main flow is to use sql to structure complex queries for starting points, and then use the graphblas to flow through the graph to the endpoints, then joining back to tables to get the relevant metadata. On cheap hetzner hardware (amd epyc 64 core) we've achieved 7 billion edges per second BFS over the largest graphs in the suitesparse collection (~10B edges). With our cuda support we hope to push that kind of performance into graphs with trillions of edges.