I've been using Zappa https://github.com/Miserlou/Zappa for a few side projects and even at work, and you can definitely set up a robust version-controlled, CI + UAT + CD pipeline if you have the discipline.

* Dev: develop inside Docker container identical to Lambda environment https://github.com/lambci/docker-lambda

* CI: test via Jenkins/GoCD/Travis/CircleCI, inside docker

* Staging: deploy to staging host on merge

* UAT: against staging env, break build if any user-facing tests fail

* Prod: deploy exact same package we deployed to Staging