That looks cool, but as you said maybe a little overkill, hehe. I'll still check it out in more detail, in any case good for later!

Thanks for the recommendation! I'll check it out. Simple sounds good for mye use case.

Ah, I see. What kind of disk usage are we talking about over e.g. one month? I am (at least for now) not necessarily interested in long term storage (but the data hoarder in me might quickly change that).

Depends on your budget, I guess. My setup consists of a regular Samsung Smart-TV that I have disconnected from the network, connected to a mini-PC from Minisforum running Linux Mint. The reason I got that was mainly for gaming, could get away with a significantly cheaper option if not. I run my own Jellyfin-server for media content (movies, TV and music) and use FreeTube to watch YouTube (which I sync with my laptop and mobile using SyncThing). I do use a wireless foldable and rechargeable keyboard with built in trackpad, but it's not working as great as I imagined. Corsair used to have a nice media keyboard, but as far as I know they have discontinued it and I haven't yet found a new one that fits my criteria, so I keep using the foldable one.

As for gaming, I run emulation through RetroArch and Steam in big picture mode. I have four 8BitDo Ultimate controllers in case I get any friends over who are keen on a round of Mario Kart.

Very much my favorite final boss of the series.

This shows up when running sudo apt update after having killed the process that is holding the lock. Where would I find out which packages it is trying to install or upgrade? It does say update-initramfs in the second line there, so I think it's trying to update?

Relevant output from df -H:

/dev/nvme0n1p1           1,1G  945M   24M  98% /boot
/dev/nvme0n1p2           536M  9,3M  527M   2% /boot/efi

[Unit]
Description = Tomte-daemon, finishes tasks that could not be accomplished before
After = network.target auditd.target
Before = oem-config.service

[Service]
Type = oneshot
ExecStart = /usr/bin/tuxedo-tomte configure all
Restart = no

Aha, that is exactly it! apt-get is called by their driver update tool, Tomte (https://www.tuxedocomputers.com/en/Infos/Help-Support/Frequently-asked-questions/What-is-TUXEDO-Tomte-.tuxedo). I actually would've seen this from the ps auxf | less command above if I had used my eyes a little better, as the top line in the output I pasted above is a sub-process running under Tomte.

Checking systemctl status tuxedo-tomte.service yields the following output:

aug. 08 15:33:56 laptop systemd[1]: Starting Tomte-daemon, finishes tasks that could not be accomplished before...
aug. 08 15:34:06 laptop tuxedo-tomte[1393]: no network found!! some fixes might not be applied correctly
aug. 08 15:34:06 laptop tuxedo-tomte[1393]: systemctlCmd: systemd-run --on-active="30sec" tuxedo-tomte configure all >/dev/null 2>&1

I guess contacting their support directly is the best way to solve this at this point.

Oh boy, don't like that sound of that...

That is correct. I used WebFAI to install, the automatic installer provided by Tuxedo Computers (https://www.tuxedocomputers.com/en/TUXEDO-WebFAI.tuxedo).

There are three partition on my primary SSD. One that is mounted to /boot (1G), one mounted to /boot/efi (512M) and my main partition that is encrypted. I'm guessing it is one of the two boot partitions that don't have enough space to update initramfs-tools?

I managed to kill the process, and the lock was released with the operation, allowing me to upgrade my system. After this, I moved all external sources out of sources.list.d and upgraded my system, and continued to add them back one by one to see if any of them triggered an error. None of them did.

When I reboot the system, the problem is back. I've added some more details in the original post.

As added as an edit in the original post, I managed to update my system by killing the process, did an upgrade with only the original sources.list and then added back the third-party repos one-by-one. None of the third party repos caused any problem when adding them back. Problem persists upon reboot. There seems to be an issue with updating initramfs at the end of every sudo apt upgrade, but that shouldn't run on boot, so I don't think that can be the cause?

Ok, so now I have managed to update my system by killing the process, which releases the lock, and then going on to do normal sudo apt updateand sudo apt upgrade. For the sake of troubleshooting, I tried to add back my third-party repos one by one, and none of them caused any problem.

However, when rebooting, the same problem happens again. In system settings, auto update was already set to "Manually" and offline updates is unchecked. I have not made any modifications to this. I did not have software-properties-kde installed, and it was also not available by running sudo apt install software-properties-kde. It suggested only software-properties-qt instead. So I could not check those settings, but in the 20auto-upgrades file, Update-Package-Lists and Unattended-Upgrades are the only lines present, and both are set to 1.

In addition, everytime I ran sudo apt upgrade, at the end some update related to initramfs fails. My disk is encrypted using cryptsetup, and as I've come to understand, I should be very careful doing anything related to initramfs when that is the case. Here is the output:

Processing triggers for initramfs-tools (0.140ubuntu13.2) ...
update-initramfs: Generating /boot/initrd.img-6.2.0-10018-tuxedo
I: The initramfs will attempt to resume from /dev/dm-2
I: (/dev/mapper/system-swap)
I: Set the RESUME variable to override this.
zstd: error 25 : Write error : No space left on device (cannot write compressed block) 
E: mkinitramfs failure zstd -q -1 -T0 25
update-initramfs: failed for /boot/initrd.img-6.2.0-10018-tuxedo with 1.
dpkg: error processing package initramfs-tools (--configure):
 installed initramfs-tools package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
 initramfs-tools
E: Sub-process /usr/bin/dpkg returned an error code (1)

Since this is buried quite a long way down into a thread, I will now also update the main post to include this update.