+1From an authoring perspective JPEG XL makes much more sense and it's important to see the benefits from a broader perspective than just last-mile content delivery to the browser (even if progressive decoding is a major benefit even there).
A somewhat more in-depth comparison and analysis of the data provided by Google can be found here: https://cloudinary.com/blog/contemplating-codec-comparisonsShort version: Real life data appears to support the case for JPEG-XL not only feature-wise,...
Excellent idea!JPEG XL seems to tick all the right boxes and would really benefit large groups of users with a full production feature set from low-end size-constrained image delivery to HDR image authoring/rendering (unlike WebP...).