There are anaconda, fully package conda env. and mini conda, with minium packagea.
Instead of exporting into yaml file or txt file, would like to export current env. into a bash executable sh file.
So, this file can be used to install env. for air gap environnments.
I'd look into using conda-pack: https://conda.github.io/conda-pack/
It's used to ship a python environment in distributed environments like YARN, where a consistent Python environment is needed across many compute nodes.
You'll develop your environment in a space where internet access is possible and install the conda-pack, then pack it up as an archive eg: conda pack -n my_env -o out_name.tar.gz, and deploy it from the archive. Once you've unzipped the archive you need to source an activate script and it should be good to go. this will look something like: source <env_directory>/bin/activate
One thing it can't do is ship a windows environment to a Linux one and vice versa. see the docs linked for more details and caveats.