On 2026-01-04 13:08, D. Hugh Redelmeier via Talk wrote: 
In fact, I think there is a move to package kernels as .efi files and let 
the UEFI firmware boot it directly.  In an EFI world, what value does GRUB 
add?  Anything beyond what an EFI shell would provide?
Yes, that's how it should be, especially after I discovered why all GRUB distros couldn't install on my machine.

/etc/grub.d/30_os-prober was the culprit.  And, solution is to turn it off (chmod -x), but you have to do it at the right moment, after grub is installed, but before grub is run.
  1. Run the installer, as usual.  
  2. When it mounts and starts to fill the partition, go to terminal.  "Live" ISO will have terminal.  "Non-live" ISO can go to virtual terminal <Ctrl-Alt-Fn>.  You'll be typing df a lot to find that "right moment".
  3. Find the process group id of your installer:  ps axf -O pgid
  4. Stop the installer's group:  kill -STOP -1212
  5. chmod -x [mountpoint of partition]/etc/grub.d/30_os-prober
  6. Restart the installer's group:  kill -CONT -1212
I was able to install Debian, Kubuntu, Fedora, and Manjaro.  Had I realized this at the beginning, I would've migrated to Kubuntu.  But, I'm satisfied with CachyOS.  All is well that ends well.

--William