Feature request: import and export layered image

[fluffy-critter]

I would like to use ucupaint to customize textures for VRChat avatars and other game assets, and for that purpose it would be super useful if there were a way to import and export layered texture setups through a file format which supports that (ideally .psd, to allow further fine detail editing in one of the many 2D editors which support that, or perhaps creating a custom file format), rather than having to duplicate the entire .blend file or using the linked resources functionality.

(If there's already a way to do something like this in ucupaint or even Blender itself, I'm not aware of it and haven't been able to find anything, so please let me know if I'm just missing something where I haven't figured out the right search terms.)