There is a file-jxr plugin https://github.com/chausner/gimp-jxr but it is 4 years old and for Gimp 2.8
Gives 8 bit conversions. This using linux https://i.imgur.com/SwfvKai.jpg I had a look around but nothing any better so far.
edit:
Again linux: a command line utility: http://manpages.ubuntu.com/manpages/bion...App.1.html
At least that gets a 16 bit tiff that opens in Gimp without that conversion warning: https://i.imgur.com/2hugLoj.jpg
.avif format ? I know that the linux flatpak Gimp 2.10.22 supports avif but do not have the flatpak installed on this computer.
Windows users: maybe run a linux in virtualbox
Gives 8 bit conversions. This using linux https://i.imgur.com/SwfvKai.jpg I had a look around but nothing any better so far.
edit:
Again linux: a command line utility: http://manpages.ubuntu.com/manpages/bion...App.1.html
At least that gets a 16 bit tiff that opens in Gimp without that conversion warning: https://i.imgur.com/2hugLoj.jpg
.avif format ? I know that the linux flatpak Gimp 2.10.22 supports avif but do not have the flatpak installed on this computer.
Windows users: maybe run a linux in virtualbox