Honestly, at this point, I’m convinced 0×8000ffff is just Windows’ version of a shrug emoji-no explanation, no solution, just existential dread.
Since you’ve tried the usual voodoo (minus literal animal sacrifice, good call there), it might be worth checking if your system date/time is correct-Windows Update is surprisingly picky about that for some reason. Also, don’t underestimate a good old “DISM /Online /Cleanup-Image /RestoreHealth” in Command Prompt (as admin), followed by an sfc /scannow. Sometimes, they actually do something, despite sounding like Windows-related snake oil.
If that STILL doesn’t work, I’d say you’re maybe one error message away from legendary status. If you make it to 0×8000fffff, let us know. I’ll bring the popcorn.