I noticed that one of the PowerApps samples references icons by name:
Concurrent(
Set(StepsPanelCodeFontSize, 10),
Set(_selectedTutorial, {Row: 1, Title: "About", Image: HomeIcon}),
ClearCollect(NavigationMenu,{Row: 1, Title: "About", Image: HomeIcon}, {Row: 2, Title: "People picker", Image: PeopleIcon}, {Row: 3, Title: "Planner", Image: PlannerLogo}, {Row: 4, Title: "Outlook", Image: OutlookLogo16}, {Row: 5, Title: "OneNote", Image: OneNoteLogo16}, {Row: 6, Title: "Pop-up lightbox", Image: PopUpIcon})
)
Does anyone know where I can optain a complete list of valid Icon names? I want to create my own collection with different icons.