Currently I'm working as a Software Engineer in a consulting company whose primary expertise is AWS. My day of work is mainly composed of integrating with AWS REST APIs and "designing" scalable distributed systems.
I'm quoting designing, because it's really just a matter of composing AWS Services to fit customers needs (provided clients are willing to throw money at cloud services - and most of the times they are).
I just feel that's not something I would like to double down on. I have always enjoyed digging into lowish level libraries like MapReduce or LevelDB and figuring out how it works with layers of abstraction peeled off. I would love to contribute to such a project and I always envy and look up to Jeff Dean and his opportunity to build such a beautiful low-level software and libraries.
Anyway, are there companies which have interesting technical problems to solve and not consider outsourcing them to other vendors? Maybe I should get a job in a company which has a well established product (preferably something used by developers) and has some room for creativity? What are those companies?
I've done "meaningful" work at companies that treated my like a consumable resource, and less meaningful work at companies that treated me like a person. I prefer the latter. My suggestion is don't jump at the first interesting work, look more for culture and career opportunity. You can find both, those jobs are not quite as rare as unicorns.
Good luck in your search.