dino Makes sense and was curious if I was reading the situation correctly.
Also it might be a good idea in general to have a mechanism to bypass ImageIO when needed if you plan to support OS versions beyond the last three (e.g. Big Sur now and Monterey after the end of the year). If bugs are found in future versions of ImageIO that could be security holes, it will be risky to use Orion with anything other than the last 3 versions of the OS. (e.g. more holes like CVE-2024-23286 but which Apple doesn't back port to older OS). Don't mean to blow this up into something bigger and just mentioning in case it helps with architecting a solution that addresses WebP now as well as future needs.
P.S.Since WebKit supports Linux, etc, but Linux doesn't have ImageIO, I assume WebKit already has a mechanism to work with other libraries/without ImageIO? Is there code there you can borrow for older macOS?