We use AWS Lambda exclusively on the product I am currently working on (3 peoples team).

- We use the Serverless framework

- Monorepo with multiple (micro) services

- Each service exposes Lambda for particular functions (e.g. Articles service exposes GetArticle, CreateArticle, etc..)

- No business logic is being shared between services, only libraries

- Three environments, Dev, Stage, Production (and every developer can also deploy its own)

- Tests are invoking the Lambda handlers directly and are mocking responses from other Lambda calls. We use Localstack to stub AWS services, such as S3 and DynamoDB.

Still, a lot to learn of course, but so far everything is working great for us.