I'm looking to make the jump from FAANG to exactly what you're describing. How do I find one? They don't seem to be easily found on LinkedIn or hacker news jobs boards.
I think the first step is probably identifying what exactly you'd like to do: smaller companies generally mean specialized roles (even if the engineers are themselves generalists). From that, there are probably local meetups and conferences in your area that are hosted or attended by smaller companies, consultancies, etc.