Isn't this what Pipenv does? What has been a downer for me is that many of the cloud providers do not support pipfiles in their serverless app services (Elastic Beanstalk, App Engine etc.)
On second thought, at least on GCP I should be able to put the pipfiles into .gcloudignore and just update the requirements.txt file with each new commit using git hooks, build scripts or a ci/cd tool.