The data being returned in the response from the Golang API server, would that be the React view components in the form of JavaScript objects?

The back end should return data, in the form of json objects, xml, plain text, animated cat gifs, etc.

Could you explain NodeJS + Golang API (option 1)? How should Golang handle the API if I'm using a NodeJS/Express server as well?

Golang + NodeJS microservice (option 2) is the same as the example I gave right? Where the client only communicates with a Golang server, which forwards the request to NodeJS/React for processing. The processed response is then returned by the Golang server.

Golang + JS interpreter (option 3), again the client exclusively communicates with a Golang server. But Golang types are translated to the equivalent React JS components. Then processed with NodeJS/React and returned as a response by the Golang server. Is that all right?

For the first option, you just consider your API endpoint as an RPC made in Golang and consume the content in NodeJS/Express.

For the second option, you're right.

For the third one, to make it simple, it's a V8 engine inside Golang. It's not another process or server.

Thanks for confirming!