I'm a 1-person development team (but I work with our Marketing Team), so I probably do things differently than some. I actually develop backwards according to traditional methods - I create an "Instructional Design Model", then sort of translate that into a first-round prototype. Then it's incredibly simple to screenshot all my placeholder objects/text/graphics, and copy and paste text to create a storyboard in Google Presentations (this makes it accessible for different stakeholders to edit text directly or comment on graphics/anything else in the modules).
This also makes it easy to step between design and development, so if it turns out there's an easier/faster/better way to do something, I just modify the prototype directly and demo for any stakeholders.
Rounds 1 & 2 typically require a "walkthrough" - I'll demo the protoype, showing others how it's supposed to run, and show the best working parts to give them a feel. By round 3 it's a "no excuses" prototype, and shouldn't require a walkthrough or explanation.
I'm still nailing this down, so I'm open to feedback :)