Which JXL supports, by the way. Tiling is mandatory for images bigger than 2048x2048, and you can construct images based on an 8x downscaled version, recursing that up to 4 times for up to 4096x downscaling.
That is awesome. In my domain, images (TIFFs usually) are up to 1m x 1m pixels and scaling usually goes 4x so that if you need 2x scaling you can just read 4 times as many tiles from the higher resolution level and downscale. With 8x scaling you need to go a level further - reading 16 pixels from the image to create 1 pixel of output. Not great but it would work and 4096 scaling would make the lowest resolution image 256 x 256 which is just what you need.