qt-avif-image-plugin VS org.gimp.GIMP

Download qjpegxl.dll and qavif.dll and copy the DLL files into imageformats folder.

libavif supports building selected dependencies locally. I have a script which builds static libaom to be bundled into libavif together with libyuv. It was necessary to add -DCONFIG_PIC=1 https://github.com/novomesk/qt-avif-image-plugin/blob/master/ext/build_local_libaom_libavif.sh Does Debian allow bundled dependencies? Because that would be a possibility how to build feature complete libavif.

KDE apps (for example gwenview) are able to open AVIF when new versions of the following packages are installed: shared-mime-info, libavif, kimageformats When you have old packages, you can still register image/avif mime-type manually and to build/install the Qt plug-in manually. If you want to try it, read manual How to install AVIF support in KDE https://github.com/novomesk/qt-avif-image-plugin

Thanks to Daniel Novomeský https://github.com/novomesk/qt-avif-image-plugin

Depending on what exactly you use Photoshop for, you can try alternatives like Gimp, Darktable, or Krita.

You could install the flatpak https://flathub.org/apps/details/org.gimp.GIMP, which might limit it somewhat.

Flatpak: 2.10.30, 2021-Dec-26

Yes, and the Flatpak is officially maintained by Gimp developers.

No, you don't.

For anyone wanting to try alternatives, Gimp is great. There's also a project called PhotoGIMP that makes the layout more like photoshop if you want that.