When Carmelo first made the the appimage it did use ~/.config/GIMP/2.10/ as its Gimp profile. To avoid conflicts it was changed to /.config/GIMP-Appimage/2.10/ It is possible to change it back, look in the Apprun file. (edit: or maybe not easily)
FWIW edit Apprun to
init_environment
export GIMP2_DIRECTORY="$HOME/.config/GIMP/2.10/"
export APPDIRS=$AILIBDIR:$AILIBDIR/gimp/2.0/plug-ins:$HOME/.config/GIMP/2.10/plug-ins:$APPDIRS
echo "APPDIRS: $APPDIRS"
If you have a 'regular' installation + an appimage, useful to keep separate. Resynthesizer for example, I keep a regular resynthesizer files in Gimp/2.10 and the branch color match + python resynthesizer-gui.py in Gimp-Appimage/2.10 but they share a common folder containing plugins -heal-selection.py...etc.
Quote:
Possibly because you can't have a file and a folder with the same name in unix/linux
That is share the same path, which they don't. for example the photocopy plugin
path to the folder is /usr/lib/gimp/2.0/plug-ins/photocopy/
but the path to the file is /usr/lib/gimp/2.0/plug-ins/photocopy/photocopy
...and secrets of the museum

Attachment:
plugins.jpg [ 88.31 KiB | Viewed 14200 times ]
My Gimp210 folder in home, (more convenient than the hidden~/.config) with a sub-folder plugin containing lots of junk. Frequently used are executable, occasional used plugins I make executable before starting Gimp up.