To simplify the installation of phasefieldx you should add it to conda-forge, see https://conda-forge.org/docs/maintainer/adding_pkgs/ on how to add a package to conda-forge.
You can checkout e.g adios4dolfinx as an example of a pure python package on conda-forge that depends on dolfinx.
This issue is related to the review here: openjournals/joss-reviews#7307