I just released a new Blender extension for blurring images and scene backgrounds: https://extensions.blender.org/add-ons/blur-hdri/

Under the hood, it uses the image processing libraries @pillow and #OpenEXR.

If you have ideas to build blender extensions yourself, join Brady Johnston and me at our talk “Extensions are Coming” at the Blender Conference next week, were we will be talking about how to develop Blender extensions. https://conference.blender.org/2025/presentations/4028/
(Recordings will be available as well.)