Had to do it for the project website. The solution was to generate inline placeholder images and substitute original src attributes with them when DOM is loaded

Had to do it for the project website. The solution was to generate inline placeholder images and substitute original src attributes with them when DOM is loaded, then back on scroll and click events. The placeholder images are JS-generated solid color PNGs downscaled to just keep the same aspect ratio. SVGs could be much easier but less supported probably.