Please state your use case for using dynamic expression files and what it contains.
Currently you cannot refer expression files from external file systems.
The situation you will run into is while developing the pipeline, the expression functions/variables you are referring to need to be validated and unless they are available in SLDB, it will not be successful.
You can make the expression library file reference an expression but it still has to exist within SLDB.
You can try uploading as a first step before the pipeline using the expr library; to upload to SLDB from an external file system.
Hope you got it.
- Write expr library file to SLDB after reading from an external file system based on whatever logic
- use the expression on the pipeline edit properties to derive it based on some logic.
Try it out and let us know.