I don't really understand what you're trying to do and how it relates to Vim's Python options.

I'd encourage you to come up with a minimal reproducible example that shows what you're trying to accomplish and how it fails. At this point, you'll most likely have a question that's fit to be posted as a "traditional" Q&A and I'd also encourage you to do so. Delete this question once you'll have posted it.

If you manage to post a little bit of code with expected and actual behaviors, this community should be able to come up with an answer that will be useful for you as well as future readers.

Having said that, inheriting a virtual environment from the calling shell (and thus relying that somebody activated it outside of Vim) does not seem like a good idea to me. I'd take measures to make sure it works no matter from what environment Vim was called.

BTW, I'm glad you found my answer to the other question useful. Did you notice there's another answer by phd that seems to be close to what you want to accomplish?