It is already widely supported by all the major browsers except Chromium that powers Google Chrome and Microsoft Edge. And the lame excuse they give for that is "Chromium has actually decided to discontinue JPEG XL support, citing a lack of interest in the format." So if you wait for Google (and Microsoft) to support JPEG-XL, you will be stuck in a kind of "chicken and egg" paradox, where you wait for Chromium to support JPEG-XL and Google waits for developers like you to implement it in your apps.