[mitchellst]

A lot of good advice here. I'd add a bit more.

I was similar to you out of school—ended up the lone techie in a small oilfield services company.

How do you grow as an engineer? Go get a job at a company that does that. It won't be hard. Based on the problem-solving experience you're getting now, you'll impress hiring managers much more than similar-aged / similar-comped candidates, because all they have done is focused on code, and your mindframe is probably somewhat permanently bent toward larger-picture thinking. This is an asset.

It might be the wrong question, though. The question is: are you sure you want to be an engineer? You have a seat at the table in a small business and a mentor who is a strong and experienced operator in the space. Don't under-value that setup for making a career. If you measure yourself against the yardstick of being a good technologist, then yeah, this is not the best setup to grow. But if tech is a skill, not an identity, then you have other goals: building a strong career, producing value in the market and capturing some for yourself as wealth. Lean into playing that game. Ponder how irrelevant it is that some 26-year-old vegan in Silicon Valley would sneer at your code quality. Make it your goal to have an ownership stake in your company or a similar one in the space—maybe one you start or acquire with leverage from your mentor—by the time you're 35. If you get this right, you will earn dramatically more money in your career than most engineers. You will face much better odds of business success than most startup founders. And frankly, the small business operator space is starved for high-end young talent. (It's not comparatively lucrative for the first 5-10 years, and people find the frequent nepotism annoying.) There are a ton of boomers with profitable businesses and no good succession plans. The infrastructure they built—or at least their customer bases—has to go somewhere.

My story: I left the small business I started in and went to a tech company, but I did it because my first firm was terribly unhealthy. (It folded soon after.) Never lost the vision for building and owning something, though.