Sorry to Necro this, but I did resolve it and wanted to post how I did it.
I ran into this today and noticed that the kodi addon script.module.pil built (i assume) by the kodi package was missing the entire binary component of the addon. eg.
/nix/store/g66kmapar06vgvb4qpvrafrn30sahqgp-kodi-21.1/share/kodi/addons/script.module.pil/lib was listed as part of the “custom python path” in kodi.log but that /lib/ directory doesn’t exist.
So I resolved this issue by copying the script.module.pil folder from the “system” kodi to the user cp -ar /nix/store/g66kmapar06vgvb4qpvrafrn30sahqgp-kodi-21.1/share/kodi/addons/script.module.pil ~/.kodi/addons/ and then copying the system pillow binaries to that addon’s /lib/ mkdir -p ~/.kodi/addons/script.module.pil/lib && cp -ar /nix/store/2nbnsasr8k7qjd57rwwr2hr9iyrwygca-python3.12-pillow-10.4.0/lib/python3.12/site-packages/* /kodi/kodi.config/addons/script.module.pil/lib/
I’m unsure why the system kodi addon is missing the binary data, but I can cheese it for now 