Triage / decision tree / simple guided entry / expert system for Drupal 8? Is there a Drupal 8 module or technique for asking a series of screening questions of visitors, and then spitting out a computed response? This might be called a guided interview, expert system, intake triage, or decision tree.

Specifically, we have client eligibility guidelines. I'd like a visitor to be able to put in their zip code, household size, and income to determine if they meet those guidelines. Ideally they get the result on the same page without hitting submit.

I have located this: https://bdsworks.org/triage-text-doc which is not for Drupal 8. I also read this previous result: Module for decision tree / guided entry. Hierarchical select looked promising, but I don't think it's quite the same thing I'm trying to do.

I also checked out the webform module, but it looks like the conditional logic isn't really aimed at this use. E.g., when testing against a specific value, there's no ability to test for presence in a list of multiple entries (like one of dozens of zip codes) or a range of numeric values.

Maybe this isn't as common a need as I thought?
This is not a common need of most websites. But, the building blocks exist within the Drupal API to create such business logic at the end of a webform or custom form.