@ldwm at the moment your best bet would be to treat this as a deployment/distribution problem
i.e. simply ship the additional binaries you need on the PATH somehow with your application, and then have some glue to send data between your binary and holochain via websockets
as you noted, this is because all happ code is wasm
in the future we plan to make the conductor more extensible so that the wasm could be aware of backing services if they register themselves somehow with the running conductor