Everything is working EXCEPT for alpha support in the GIMP plugin for jxl files.
JXL works with the glib plugin,
shows up in arox thumbnails (the rox-filer file manager)
converts via imagemagick -- uses scripts to give conversion option
in both spacefm and arox (png2jxl and jpg2jxl)
Default viewer for jxl set to gthumb
Also recently updated file handling for office formats.
(Basically "tightening up" file handling

Candid Note:
I use arox (he rox-filer deriv) as a thumbnail viewer,
it gives me near infinite ability to throw options in for any image type --
and I use them to manipulate images in my clipart site.
I know some follks won't have any use for the particular manipulations I do
(like jpg2pdf -- in a very specific size)
such manipulations are the reason I use Linux,
so they go into the distro

Sunday, 05/09/2021
Extra/chromium-90.0.4430.93-x86_64-1AL.txz
xap/gimp-2.10.24-x86_64-2AL.txz
Added jxl to mimetypes.
Be aware that transparency in jxl files is not being handled
by GIMP plugin pproperely at the moment.
a/etc-15.0-x86_64-20210509AL.txz
gthumb views jxl files by default.
Set in /usr/share/applications/mimeapps.list
xap/arox-20210411-x86_64-5AL.txz
Linked convertors for png and jpeg to jpeg-xl