My first thought was Ofnuts plugins which goes like this: https://i.imgur.com/bj8B9Dk.mp4
If you do not have python support and the ease of a fix here depends on distro - you should tell us what you are using. It can be done using guides and splitting up the image into layers.
Two addons for that, a script for the guides guides-grid.scm and a compiled plugin, guillotine-into-layersx64 The latter quite old, might work with your linux or might not.
A bit tedious but quick
Set up a grid of guides
Split that up into layers
Invert the layer stack
Space out with the align tool
Image -> Fit canvas to layers followed by Merge layers.
Another 50 second demo https://i.imgur.com/qioYhxN.mp4
Just in case you want to give that a try, the script and plugin attached.
If you do not have python support and the ease of a fix here depends on distro - you should tell us what you are using. It can be done using guides and splitting up the image into layers.
Two addons for that, a script for the guides guides-grid.scm and a compiled plugin, guillotine-into-layersx64 The latter quite old, might work with your linux or might not.
A bit tedious but quick
Set up a grid of guides
Split that up into layers
Invert the layer stack
Space out with the align tool
Image -> Fit canvas to layers followed by Merge layers.
Another 50 second demo https://i.imgur.com/qioYhxN.mp4
Just in case you want to give that a try, the script and plugin attached.