I remember reading somewhere about a self hosted application that would work like a proxy. But not http/https like NPM but all the network traffic.
I may be misremembering but what caught my attention at the time was the possibility to log communication packets. It was months ago and I ended up forgetting about it.
My use case would be monitoring communication with a device I’m developing an app for.
Lots of them, if you want something large and powerful you could set up security onion, mirror a port and it’ll capture everything plus graph and slice up things all over. Needs a fairly hefty box not to choke if it gets fed a lot though.