I discovered the world of
medical devices by accident and it’s great. When the bosses are nice, it’s pure heaven.
I write code in C# or C++ (but also Python, pipelines, scripts, JS, etc.) and it needs to be somewhat efficient. We all follow the same rules (62304 especially), we must write unit tests, and make sure that my features are properly integrated at all steps of the development up to the release, and even after when you must validate it with the authorities, when you have bugs, etc. If you're in a small company, everyone can be involved in all the processes and it's fun because you go much further than mere development (like preparing reports for various agencies all over the world, or helping PhDs integrate their code in the application).
We have commit hooks to check and format code, pipelines must be green. You cannot cheat because someone will find out. And you can’t pretend that your code worked once on your computer because the test team will refuse your code if it breaks anything. It’s more rigorous at all steps of the development.
Last but not least we have specifications for everything because it’s the law. Overall it’s what software engineering should have been all the time. It feels like working at NASA even if it's only a stupid desktop tool or application.
Of course everything is not perfect, you can stumble on assholes like every other company, but it's not everywhere. I’m happy to go to work every day, I may have saved a life or two with my code, and that's a good feeling.
My experience comes from having worked with the biggest assholes on the planet at different companies. To answer your question, I would say that an interesting job is rigorous, peaceful, and has some kind of meaning.
Edit: as another guy said, I too settled for lesser wage to work for a company that would not destroy my soul and spirit. That's important too.