Dear Craig,
Good day!!
I understand your concern and to my experience & test, it seems the image in the first screenshot is created with the help of the Designer feature in the PowerPoint presentation and to my knowledge, there is no feature in the PowerPoint application to convert Icon Label List to the SmartArt library in the PowerPoint presentation.
Moreover, from my search, I found the following article: SmartArt With Icons from PowerPoint Designer in PowerPoint 365 for Windows (indezine.com)
In this situation, I agree with you having the ability to convert or save the icons list to the SmartArt library in the PowerPoint will benefit the users and suggest you to add your valuable idea as a feedback in the PowerPoint · Community (microsoft.com) which is the best place to share our ideas and improve the Microsoft PowerPoint product.
In addition, I will keep this thread open so that PowerPoint MVPs and experts in this community will share their opinions on your concern.
Appreciate your patience and understanding with us. Have a great day!!
Best Regards,
Sophia