You can run Armbian just fine only from SD card, I do that on a Beelink box, you do not NEED emmc to work. Did you get picture on the monitor?

Hello good people, it's update time! I have made a bit of progress but got stuck again. Here's what I did : I have tested the pads I found next to the SDCard and indeed, they were serial connections. With a little bit of brain power and luck, I figured out that the one with the square pad is GND, and both in the middle are tx/rx. Please don't judge my deskmat... Once that was done, I was able to connect to the serial port through a terminal and armbian surprizingly booted. I was able to test the 3 different DTBs that are supposedly compatible with my board and all of them booted, though with no luck of getting the eMMC working. I then got the idea to find the dtb of the original android install and got to work. I was able to extract a dtb.img file, which after some work, got 2 dtb files out of it, supposedly for both 1G/8G and 2G/16G versions of the board, the later being mine. Sadly it does not work as is, but I believe that it gives me enough information to keep going. But here's the road block, no matter my attempts yesterday at trying to get the correct code inside of the dtb file, nothing would get the emmc to work. Otherwise everything works fine, the armbian install for that board is not the cleanest but after fixing a few things, I was able to ssh into it through network and work on it from there. If there's a kind soul out there with dtb manipulation skills, I would be grateful to get help from you!

@Igor is the case, I upgraded from bookworm to trixie

this can easily be answered with a quick web search or AI request for "disadvantage of LPAE on armhf". As expected, one of the drawbacks is increased use of memory when the benefit of larger addressable memory applies only to few installations and in a limited way.

OK, this is the line that is problematic. You need to find out why sda2 is mounted read-only. Go through the logs, for example "sudo grep sda2 /var/log/syslog". If you can, boot from a different medium and fsck sda2.