ProzillaOS is designed in Figma by Prozilla. You can view the design file here.
The font used by ProzillaOS is Poppins from Google Fonts by Indian Type Foundry, Jonny Pinhorn.
ProzillaOS uses Font Awesome icons (some modified) in its UI.
The apps use icons that are either modified versions of FontAwesome icons or custom icons, designed by Prozilla.
The color palette is the Canadian Palette from Flat UI Colors 2 by Ahmet Sulek.