The "single pixel buffer" Wayland protocol extension provides a way for clients to create 1x1 buffers with a single color, specified by providing the color channels (red, green and blue) as well as the alpha channel as a 32 bit unsigned integer.
For now, this is turned into a 1x1 texture. Future potential improvements is to hook things up to the scanout candidate logic and turn it into a scanout capable DMA buffer.