It looks like #GNOME is ready to embrace #jpegxl into its ecosystem! Wallpapers are being switched to JXL from WebP, & GNOME Web will adopt JXL support through WebKitGTK. The GNOME SDK is also going to be built with libjxl from now on!
https://gitlab.gnome.org/GNOME/gnome-backgrounds/-/commit/ccbdb7d2ea5dbd1f2b9de4be348dfa0ab286d76c#22c413786be8450c02034a0b002a5831a801c29d
https://gitlab.gnome.org/GNOME/gnome-build-meta/-/merge_requests/1622#note_1780272