Dotlock https://pypi.org/project/dotlock/ is a package management tool similar to pipenv, but with a different philosophy: instead of acting as a wrapper around pip, dotlock handles package resolution natively. This should allow for more flexibility, better performance, and a smaller surface area for bugs, but at the cost of the wide platform and package support the pip developers have put so much work into.
Dotlock is still very much beta software, and currently the only users are myself and my company. It works well for our use case (deploying web applications to linux servers), but has some gaps in support I know about (including packages that use setup_requires or pyproject.toml), and probably many I do not. Thanks to everyone on this list who I discussed dotlock and general package issues with at PyCon, and to anyone who tries it out!