I use it with standard venv these days. Works fine. Just remember to set Far Manager command line prompt to %PROMPT%, see Options->Command Line Settings->Set command line prompt format. It should be checked and contains the above mentioned environment variable.
reg
Thank you, great tips! Came here to get prompt for standard python venv in Far manager. Still couldn't make the prompt, but FarCall and %PROMPT% are great tools to use anyway.