IconFontsImageList components by @Carlo Barazzetta could be the answer: you can explorer the complete wiki to see how it works.
Summary of library:
An IconFontsImageCollection component that inherits from Delphi's CustomImageCollection and is compatible with VirtualImageList
A IconFontsVirtualImageList, to use with Delphi version older than 10.3
A rendering engine of Icon-fonts using GDI+ (from Delphi XE4)
A complete backward compatibility with older Delphi versions (from Delphi 7)
A useful Collection and Component editor, with support for Category of Icons
A custom CharMap viewer, to easily select icons contained in any Font
Support for changing the Color based on the active VCL Style.
High performance of drawing engine
Support for FMX (also for mobile platforms)
It's free and open-source
Icons based on Fonts are a good alternative to bitmaps because they need only the Font installed in the system to obtain thousands of images (like the "Material Design Font Desktop.ttf" font: https://github.com/Templarian/MaterialDesign-Font). The icons scales perfectly, so, you don't need to multiple resolutions of your images to match the DPI of the monitors and multiple colors for Theme used.
The Collection of Icons can be rendered by a single Font/Color defined at collection level, or by different Fonts/Color defined at Icon level, so you can mix different icons from different Fonts in a single collection.
The library is quite stable, but any contribution is welcome!