The geeqie “edit > open with …” are called plugins. You’ll run into this when you go to the geeqie configuration/preferences and edit a “plugin”.
Geeqie pretty much adheres to the unix philosophy of keeping tools simple. Don’t expect a huge plugin for opening raw images within Geeqie! The task is off-loaded to other more dedicated viewers. (At most, Geeqie currently will display the embedded JPEG within a Nikon NEF raw image for the preview/icon image.)
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