UWP Apps File Association?

Hi forum,

Does anybody know how the UWP apps file association work? They have no "EXE" file, but they can be associated with file extensions in Win 11. How?

I want to associate WEBP (Google JPG/less lossy format!) with Photos App. It doesn't support WEBP natively (Microsoft Edge can open this format natively). By downloading and installing "WEBP Image Extensions" from Store, Photos App can open WEBP. Of course, first, you have to rename the WEBP extension to JPG or any image format like PNG, TIF, or GIF!

Also, I want to Associate ICL and ICO files (with Photos App).

Windows Photo Viewer is a dynamic library or DLL (and has no "EXE" file). There is a registry hack to associate images with this app. Is there something like this for Photos App?

They do have executables.

The directory maybe slightly different

I have tried that (I am aware of the UWP app folder's path, and I can access it by Registry without taking its ownership). It doesn't work! The interesting thing is the UWP "EXE" files have no icons. Instead, their icon files are collected in a folder as "Assets" as PNG files. AFAIK the "EXE" files don't accept PNGs as an icon. I think all those things (app icon and file association) are controlled by an XML file, not directly by the "EXE" (and Registry). I am not a programmer! Just my guess.