So, really, no commercial "cloud" product meets these needs? So many other industries are beyond managing hardware; seems like an obvious opportunity for a product.
Azure supports RDMA over IB on certain node types but (my 2 cents) without more detailed information & control over topology it's hard to run non-trivial MPI jobs in anything close to an optimal way. The hiding of the "secret sauce" that cloud vendors do may not be important for most commercial users but it's a roadblock for a lot of HPC.
At that point you just call it a supercomputer. Private companies already buy time on government/academic supercomputers, so I don't know if there's a compelling opportunity there since your startup costs would be immense.