GO = you can build apis but they're faster
Rust = new C++ and really fast
it seems to be best supplementary language combo to learn would be
Go/Rust or Nodejs/Rust
this way you know one good web/api language and one really efficient language.
Having said that, it depends on what you want to build.
In my opinion, Go is great for building command line applications, infrastructure applications (Kubernetes and related stuff), your own database, a DNS server, or anything you would otherwise use C/C++/Java? etc.
If the answer to the question: What would I write this in if Go didn't exist? is C/C++, etc... then Go is what you're looking for. If the answer is Python, Ruby, php, etc... then node is a better fit (compared to Go).
For building Web Applications, and web realted APIs, again in my opinion, what you need to focus on is in the ecosystem, not the language. You need to focus on the libraries, the frameworks, the tooling, the editors, the ORMs, the validation libraries, etc, etc.
In this regard, I think the node ecosystem is a lot more suitable. You might need to do scraping of other websites, generate PDFs, access a database, render a preview from an url to an image, etc. Node has an infinite amount of useful and popular libraries for all web stuff.
At my previous job everything in the backend was being rewritten in Go. The inseane amount of reinventing the wheel and wasting time on things already given for free in other ecosystem was astounding. To me an extreme example of this was the "We dOnT NeEd OrMs iN gO" and then see the team suffering weeks to do the right migration statements in SQL files executed by custom bash scripts and creating manual CRUD queries for trivial data which, with the Rails ORM, the Django ORM or Prisma.js would be literally 30m of work, migrations and deployment included.
But hey, Go is so fast! So go ahead with Go if you're already FAANG scale.
Python will do the job. Java-shops still chug along. Go-lang is nice. Node-js is fine.
But if you plan to run in the Kubernetes ecosystem, Go has some nice things, and is usually simple and has the 'one obvious way to do it' vibe.
I used both GO and Node 'in anger', and one was not obviously better than the other.
Since I value simplicity, productivity and ease of deployment, I would say that Go is the best server language out there.
Now, if you‘re learning for the job market, probably Node is king, even though Go is constantly gaining popularity.
As a node dev, if I'm chasing performance I'd look for libraries with c++ bindings, like uWebSockets for example.
NodeJS internal apis also got cluster and worker_threads which are handy when distributing workload in multiple cores.
On the other hand if you're talking about faster dev speed, nodejs is ok too since i can reuse some modules in backend and frontend.
Of course golang has advantage in terms of types (i abuse assert in nodejs to makeup for this) and performance (i throw money on hardware instead, if really needed), but question is do you really need those right now? The answer greatly varies per project.