But I'm struggling to find a way to actually point openWRT endpoint towards my Go script. For example, the instructions he provided said once you compile you can just curl the IP address. Does anyone know how to set this up with Uhttpd/Lighttpd? Or do I not need them to be able to host this API?
Tldr: How should I setup a basic API with GoLang on OpenWRT?
Your go application does serve the http requests itself, no need for an additional http server.
Write the go code for you api or what ever as in your linked example, cross compile it and run it. Then you can access this http endpoint with any http client, for example curl.
That's really interesting I didn't think it could sevrve the http requests itself. I thought it was simialr to Lua/Php which needs a http server & fastcgi config.
Also, to have this part of my OS I assume I just need to add the app to the bootscript to have it running permanently as an API?