I was searching through Visio User Voice https://visio.uservoice.com/ for ideas of shapes to create and came across a request for converting text to outlines, something Adobe has. The feature does not exist in Visio, but it does exist in the other Office products like Word and PPT. So the easy answer is to create the graphic there and copy to Visio. Of course, this sounds easier than it is. What you copy to Visio may not look like what you expected so, ungroup the new shape. Drag the top shape above the others, select the top shape and the rest and distribute vertically. This wil show you the shapes you brought in to Visio. Throw away the unpromising ones and one of the rest should be a shape outline you can fill.
I did find a shape to create, an oscilliscope with changeable line patterns. I did find a suitable SVG image and was able to disassemble into component shapes. Now to reassemble with Visio smart shapes. 😉
I hope you find this useful.
John… Visio MVP in x-aisle