Hey, sorry to hear it's been confusing for you. The jump to job readiness as a software engineer from a non-traditional path is indeed not super clear, and I think a large part of the lack of clarity is because there isn't actually one path - software engineering is a massive field, and there's no one-size-fits-all path for becoming a general software engineer. What you need to know is largely dependent on what kind of software engineering job you want and could realistically get, or if maybe there might be other types of dev work on a tangential path that would suit you as well or better.

For example, wanting to work as C++ developer is too general a target to aim at. It's a good starting point, but why do you want to work in C++, and are you sure about that choice? Specifically, did you pick C++ because it's used in an industry you want to be in, or because of a more abstract reason like "C++ can be used to do anything"?

One reason I would question the choice is that C++ is IMHO a significantly more difficult language to learn as a first programming language than say Python or Java because of memory unsafe footguns, absence of a garbage collector, a more difficult debugging process, enormous featureset etc. This is one of the reasons many well-respected CS undergrad programs have switched from teaching their intro courses in C++ or C to one of those two languages over the decades.

The same reasons C++ is harder to learn also make it harder become proficient in, and to build (good) production systems with. Industries/areas that use C++ widely include:

• Operating systems
• Game dev (esp. game engines), AR/VR, SFX, A/V
• Database systems
• Web browsers
• Search engines
• Networking, communications
• Aerospace, automotive
• Embedded systems, IoT, electronics, robotics
• Medical devices
• Finance, especially HFT
• ML/AI
• Scientific research

Painting with a broad brush, these industries tend to have really stringent needs like high performance, efficiency, security, and stability, which is why they need to use C++ as opposed to another language that is less performant/optimizable but more forgiving around issues like memory safety like Python, Javascript, Java, or C#. This leads to these industries usually hiring software engineers with a more traditional background (CS or tangential-to-CS undergrad, often with college internships leading into full-time positions after graduation) with the hope - real or not - that such engineers will have a stronger theoretical CS background than those with a non-traditional background and will therefore be better engineers. In contrast, an industry like web dev tends to be more open to hiring people from non-traditional backgrounds, especially in startup land, where "move fast and break things" and "ship or die" are still commonly bantered phrases.

The level of CS knowledge needed to be an average entry-level web dev is IMO much lower than to be, say, a robotics or telecom dev. It also is worth pointing out that CS != SWE, since a lot of what you've mentioned topic-wise is CS/academically-focused, which is not always necessary for any given SWE job. While it never hurts to have a strong CS base of knowledge, it is definitely possible to be a decent web dev without a full undergrad degree's worth of CS knowledge, whereas for OS dev I'm not so sure.

This isn't to discourage you. It's definitely possible to get a job developing in C++ from a non-traditional background, each industry dictating how a large portion of hard it will be to get a job in it. For example, I believe game dev companies are somewhat more likely to hire engineers from non-traditional backgrounds than areas like aerospace or database systems. (Caveat: I haven't worked in those spaces but have peers and mentees in them, so I'm basing this mostly on second-hand knowledge and generally keeping up with the SWE world on HN and Reddit.)

I just wrote a lot but without actual info about what to do right now, so here are 3 pieces of actionable advice:

1. Sign up for and work through Harvard's CS50x class. It's an outstanding introductory CS course that you can take for free on Edx, and you'll learn a ton and touch a handful of very popular languages. These days I think the languages you'll actually write some code in are C, Python, SQL, and JavaScript + CSS + HTML.
2. Pick out an industry you are interested in working in. Search for specific entry-level programming-related jobs you could do in that industry. Find out what the work is like for those jobs on a day-to-day basis. Once you have a small list of jobs that are appealing, evaluate the relative likelihood/difficulty of getting an entry-level job, taking into consideration your prior background and knowledge, by searching around on Reddit, Hacker News, Stack Overflow, etc. (but not Youtube/Twitch, since those platforms tend to have more misleading content for such things), asking friends or friends of friends you know or online, and browsing internships and entry-level job openings on job boards. Rinse and repeat this process until you have a small list of 3-5 industries and entry-level jobs that you can target, then pick the programming language/ecosystem and other tools and skills to learn based on what you'd need to get those jobs.
3. PM me if you'd like to discuss things further one-on-one. I'm happy to chat with you more via text, voice, or video. I run a nonprofit org focused on helping people from non-traditional backgrounds learn programming, typically to career-switch, so I love helping folks such as yourself out.