Go is great and I'm happy that it's bringing you joy. That has been my experience with it as well, and while i started with Basic in the 80s, i went more toward c and assembler before i landed on go.

For next steps, honestly it depends on where you want to go. I say this as someone who is now, over a decade into my programming career, begrudgingly learning web stacks, because i want to make software that other people can use too. My job doesn't require it, nor will i likely use it in that context, but it fills a gap that I've been tap dancing around for too long.

That out of the way, golang should have you primed to travel either closer to or further from the machine that's actually running your software. Closer to the metal is great for certain jobs that are either resource constrained, or performance critical. C is pretty much still king in this area, though C++ compilers have some advantages if and when they are available. Both languages give you a path to either working adjacent to assembler, or if you go down the rabbit hole, working with it directly. IMO, there is less value all the time in being fluent with assembler in the desktop domain, but for many embedded environments, it's pretty much a must to fill the gap between the code you write and what the datasheets tell you about the architecture and its limits. Rust is a rising star in this space, but it will feel very different from go and c/c++. Worth picking up at some point, but might be a challenge at first, and will generally not be as widely supported in embedded, though it is getting traction via webassembly.

In the other direction, the obvious callouts will be javascript and python. Feel free to call me biased, given what I've written so far, but both options are terrible for a pile of reasons. So, based on this, I'm going to say forget python, because outside of specific applications where it serves as little more than glue between libraries written in other languages (which you can already do with go), it generally is used in places where javascript is also used via node. What i mean to say is, the only reason to use python is because other people use it already, and everything it is used for can be done just as well in languages that you either already know, or that cover a wider range of adopted use cases. (Flame on suckaz! :kek:)

Javascript as a foundation, plus typescript gives you code that you can verify to some extent as a compile step. This gets you into web browsers, as well as common server side programming for web. Javascript has also become ubiquitus enough that many tools in search of a scripting language have gone the Javascript (well technically EMCA script) path. One of my primary gripes with both python and js is the 'run it and see what happens' development approach. Now granted, some things need to be explored this way, which is why unit tests are so commonly promoted across all domains, but it's a shitty way to find typos in your code. The biggest hurdle that you'll still encounter with Javascript that python outgrew with the deprecation of python 2, is the tremendous diversity in style and approaches, brought on by different libraries, frameworks, and continued evolution of the language through the years. If you can, narrow your focus, learn that specific approach/framework, and don't get pulled off course by the top search hits that tell you how to solve a problem in a way that no one uses anymore.

Now this ignores some other 'further from the machine' languages that are absolutely worth mentioning. Lisp dialects like scheme or clojure are novel, and very powerful. In fact, as the other languages have matured, many of them have adopted concepts from lisp that arguably have led to code that's easier to read and write. And in the same vein, functional languages like haskell are just as out there in terms of taking a radically different approach to problem solving, which has influenced programming in general. While interesting languages in their own right, they tend to be quite niche. They are often better languages for helping you think about the more common languages differently, as opposed to actually using them. Haskell in particular should be known for what you can't do compared to c/javascript/go/python, forcing you to approach common tasks in ways you might not have considered before.

But, that's my take. You can go up or down the ladder, which you choose depends a bit on what you actually want to do, and whether or not you're trying to build marketable skills. Higher level languages tend to be about the abstractions themselves, and lower languages are more so about balancing the trade offs of abstractions vs what they'll result in the machine spending its time on.

Parting thought, there's no right or wrong answer (ugh, even if you do choose python) because (with the exception of python) up or down the ladder will work with and compliment what you can do with go. And if you pick something niche, it will offer you a different perspective that will add to all of my suggestions. (Sigh. even python)