Context: Even though Chromium has native support for AVIF, a very nice image format, Microsoft goes out of their way to remove it from Edge, which is a chromium fork. Jpeg XL (JXL) (not to be confused with Jpeg (JPG) or Jpeg 2000 (jpg2k) ) is another nice image format, which, IIRC, is only supported in Firefox.
Let’s rename JXL to GPEJ to give GIF pronunciation a run for its money
When it comes to pronunciations of obscure computer acronyms, my favourite is btrfs (the filesystem), because I’ve never seen anyone advocate for any specific pronunciation, not even the devs/official documentation. Bee Tree Eff Ess? Bee Tee Arr Eff Ess? Butter Eff Ess? Better Eff Ess? Whatever bloats your goat!
butt terfs