Update: I’ve asked around on Mastodon, and lo and behold, @gluebyte@mastodon.social had an answer!
Use a built-in Dictionary action, set the keys to your questions, set the type to whatever, and set one value to the built-in “Ask Each Time” placeholder (enter the value field, right-click it, Insert Variable → Ask Each Time. This will pop up the entire dictionary in a dialog when the workflow is executed, and allows you to fill in every available value. I’ve made a quick video:
Once you’ve filled out all the fields, the action will return a bog-standard dictionary which you can then dissect as usual.
Hope this helps!