Ideally you would use an image label and set it to have pixelated resampling. This would use the most reasonable amount of memory.
If you absolutely need to have a dynamic set of pixels, there is a great resource on the forum that you can use to do this:
It’s very well optimized for drawing pixels, though be warned it will probably still take somewhat significant amounts of memory. If possible, I would create a set of images and cycle through those instead.