My dayjob is a rather efficient path to earning money with esoteric skills I have, but my side activities and income generally line up with my goals towards sustainability and the like. I rebuild electric bike battery packs (as an alternative to replacing an old system with a brand new system, when the old one just needs some new cells), do general research in that area, and am working on a line of products for homesteads (irrigation, initially, but also other sensors) that are open source, hackable, and local - no reliance on remote "Teh Cloudz!" services. And focusing on energy efficiency there so I can run them on as little power as possible - no need for massive solar panels or such when I can do it with a small solar panel and capacitor.
And I'm working towards some useful products for electric bikes, along the same lines - while I don't ebike nearly as much now that I live in a rural area on a 55mph road, I still think there's a lot of value in them, and there are some niches that are not filled.
In some ways, yes, they're "consumer products," but they're opposed to the normal consumer products of "Shiny, new, internet, cloud, and don't you dare try to fix it." My stuff is quite clunky by modern terms, but is the electronic equivalent of my old tractor (75-ish years old) - simple, straightforward, and designed to be maintained by someone of limited skill. Or, at least, they can trust that it's not going to be easily compromised. I doubt any of the stuff I build will outlast my tractor, which I consider myself simply a caretaker of for the future generations that will use it.
