From the link
> To address this concern, the team at Google has agreed to apply their subject matter expertise to build a safe, performant, compact, and compatible JPEG-XL decoder in Rust, and integrate this decoder into Firefox. If they successfully contribute an implementation that satisfies these properties and meets our normal production requirements, we would ship it.
That is a perfectly clear position.
How far away is JPEG-XL rust version from Google if Chrome is not interested in it?
You can review it here: https://github.com/libjxl/jxl-rs
Seems to be under very active development.