your machine confuses me a bit, it has errors only happening in your side... like, everything goes good reading the logs until some moment that appears this:
Removing libfontembed1:amd64 (1.28.17-3+deb12u2) ...
dpkg: error: parsing file '/var/lib/dpkg/status' near line 5735 package 'elive-menus':
first (want) word in 'Status' field: has invalid value 'instanl ok installed'
dpkg: error: parsing file '/var/lib/dpkg/status' near line 5735 package 'elive-menus':
first (want) word in 'Status' field: has invalid value 'instanl ok installed'
E: Sub-process /usr/bin/dpkg returned an error code (2)
E: Sub-process dpkg --set-selections returned an error code (2)
E: Couldn't revert dpkg selection for approved remove/purge after an error was encountered!
[ WARN ] Package overwrite conflict detected. Forcing dpkg configuration with overwrite...
W: Package overwrite conflict detected. Forcing dpkg configuration with overwrite...
[ WARN ] Command failed (exit code: 100): apt-get full-upgrade -y -o Dpkg::Options::=--force-confdef -o Dpkg::Options::=--force-confold -o Dpkg::Options::=--force-overwrite --allow-downgrades --allow-remove-essential --allow-change-held-packages -o APT::Immediate-Configure=0 -o APT::Force-LoopBreak=1. Attempt 1
of 5. Error: dpkg: error: parsing file '/var/lib/dpkg/status' near line 5735 package 'elive-menus':
first (want) word in 'Status' field: has invalid value 'instanl ok installed'
E: Sub-process /usr/bin/dpkg returned an error code (2)
what? "instanl" ? 
the "l" was changed to "l" without reason. There's no instanl in the source code and you are the only one to have this issue... why ? only one thing comes to my head: hardware issues (altering your bits), or you are in an area prone to many cosmic rays 
, or microwave, who knows...
At this point i suggest checking your hardware (especially RAM, and then CPU), following this howto: How to verify for hardware problems, keep your computer healthy
Oh, and you should fill your HD full of zeroes if you didn't do it before the auto upgrade, run smartctl with "on" and then fill it with zeroes, then install auto parted
Mmmh, everything else in the logs looks OK and correct.
Does your "apif" shows something remaining to install ?
using openrc ? make sure to always "apug" when you have a bug, i yesterday fixed something about treboots
but in short it looks good, you have only a few issues on your side but first as said i would look into hardware health first. After to confirm (and/or) repair your hardware issues, you can see what is happening on your side that makes you: cannot reboot/shutdown (seems like it works in other openrc machines) and why grub doesn't shows up (this can be simply a wrong configuration / compatibility in your side, try to edit your /etc/default/grub to see)