Pixel-perfect UI sprites for multiple resolutions

I am trying to figure out the intended workflow for rendering pixel-perfect UI sprites for any / supported screen sizes. So far I figured out I need to use constant pixel size canvas scaler, pixel perfect canvas render mode and native sprite rect sizes. That causes sprites to be displayed large on small screens and vice versa. Therefore I guess I need to have multiple sprites and somehow swap them, while also maintaining its rect size to always keep native size. The built-in sprite variants give me no control over the downsized atlas content, all it does it uses some default downsampling technique, I am not able to downsample and create a sprite atlas on the fly (as the sprite atlases seem to be read-only in runtime). Therefore I cannot compose my own sprite atlas from sprites that I generate using some advanced downsampling, nor can I generate sprite atlas variants in the editor. All I can think of at this point is to have an Image component accompanied by a script that swaps and resizes the image (selecting the most appropriate size) at runtime, without being able to use atlases at all. I could write some custom solution if I could build atlases at runtime. Is there some intended workflow I am missing completely, or is this left completely unsolved?