Meanwhile, there's still no support for dependency specifiers/environment markers (PEP 508/PEP 345) in environment.yml files, and the documentation is VERY sparse about what is supported: https://conda.io/projects/conda/en/latest/user-guide/tasks/m...

At least they support ~=3.9 and >=1,<3 comparisons (although this is undocumented as far as I can tell.