I am attempting to import a .jpg file/photograph to set up as a "wallpaper". The resolution is exxactly 1080x2400, as is the screen on 6a. Illustration (reduced in size for inclusion here) is:
https://i.postimg.cc/fRHFzRBp/problem-Xmpl-A.jpg
After following the steps in Settings - Wallpaper and style; the wallpaper On Home screen looks lke this:
https://i.postimg.cc/bJbpSt5s/problem-Xmpl-B.jpg
For reasons I can't figure out, the software on the 6a is attempting to erroneously fit/resize an image that already has the exact resolution of the screen? I see no UI control element that would tell the process something like "do not fit/resize..."?
Any suggestions are appreciated.

Yes, further research convinced me that it is the consequence of the ill-advised animated wallpaper feature Google "invented" in Android 11, and which no one seems to be able to turn off. This is confirmed by the fact that if I use the same "native screen resolution" image file for the lock screen, the photograph is displayed flawlessly there, but is mangled on the Home screen as in the example I posted above.
It would be nice if GrapheneOS could dispense with such useless fluff, but I understand why the developers have more pressing tasks to attend to...