I appreciate the link!
This at the very least will help me to understand protocol better. Wading through API documentation is not the most interesting of activities!
I agree. I hope my code is helpful (or perhaps it already fulfills your needs). My project ended up as an exercise on learning to use asyncio allowing multiple network connections in a single CPU thread (making resource locking/concurrency issues much easier to handle). I ended up being able to serve local USBTMC instruments over the local network, and connect to it with NI VISA for Windows. Getting back to the original question, Benchvue will work without any fuss, as long as you use HiSLIP or VXI11.
Another caveat I should have mentioned was security: Neither VXI-11 nor HISLIP have any ability to encrypt their communications. VXI-11, since it uses SUN RPC, can handle arbitrary authentication methods, but the data wouldn't be encrypted and the NI/Keysight VISA don't handle authentication, anyway.... HiSLIP 2.0 will support TLS, but the protocol is not yet released.
If you need security, you'd want to tunnel the data over SSH or OpenSSL (something which the NI and Keysight VISA wouldn't be able to do internally). VXI-11 uses a pair of TCP sockets (which would need need to be registered with a portmapper on a third port; the portmapper doesn't need to be on the same host as the VXI11 server) while HiSLIP uses a single TCP port (and thus would be easier to tunnel).
I don't think that the commercial gateways provide secure connections, either.