Rootfs location is passed via kernel parameter, for example my grub.cfg has “set root=‘hd4,msdos1’”. That’s used by kernel and initramfs to locate the root filesystem and once ‘actual’ init process starts it already has access to rootfs and thus access to fstab. Initramfs update doesn’t affect on this case, however verifying kernel boot parameters might be a good idea.
Just in case you end up with reinstallation, I’d suggest using stable release for installation. Then, if you want, you can upgrade that to testing (and have all the fun that comes with it) pretty easily. But if you want something more like rolling release, Debian testing isn’t really it as it updates in cycles just like the stable releases, it just has a bit newer (and potentially broken) versions until the current testing is frozen and eventually released as new stable and the cycle starts again. Sid (unstable) version is more like a rolling release, but that comes even more fun quirks than testing.
I’ve used all (stable/testing/unstable) as a daily driver at some point but today I don’t care about rolling releases nor bleeding edge versions of packages, I don’t have time nor interest anymore to tinker with my computers just for the sake of it. Things just need to work and stay out of my way and thus I’m running either Debian stable or Mint Debian edition. My gaming rig has Bazzite on it and it’s been fine so far but it’s pretty fresh installation so I can’t really tell how it works in the long run.
I’d argue that if the plan is to run Debian testing it’s at the very least beneficial, if not mandatory, to learn some basics of the terminal. Debian doesn’t ship with sudo by default, so it’s either logging in directly as root or ‘su’. Instead of vim (which I’d personally use) I’d suggest nano, but with live setup it’s also possible to use mousepad or whatever gui editor happens to be available.
I suppose it’d be possible to use gparted or something to dig up the same information over GUI but I don’t have debian testing (nor any other live distro) at hand to see what’s available on it. I’m pretty sure at least stable debian installs with UUIDs by default, but I haven’t used installer from testing in a “while” so it might be different.
The way I’d try to solve this kind of problem would be to manually mount stuff from busybox and start bash from there to get “normal” environment running and then fix fstab, but it’s not the most beginner friendly way and requires some prior knowledge.
Do you happen to have any USB (or other) drives attached? Optical drive maybe? In the first text block kernel suggests it found ‘sdc’ device which, assuming you only have ssd and hdd plugged in and you haven’t used other drives in the system, should not exist. It’s likely your fstab is broken somehow, maybe a bug in daily image, but hard to tell for sure. Other possibility is that you still have remnants of Mint on EFI/whatever and it’s causing issues, but assuming you wiped the drives during installation that’s unlikely.
Busybox is pretty limited, so it might be better to start the system with a live-image on a USB and verify your /etc/fstab -file. It should look something like this (yours will have more lines, this is from a single-drive, single-partition host in my garage):
# / was on /dev/sda1 during installation
UUID=e93ec6c1-8326-470a-956c-468565c35af9 / ext4 errors=remount-ro 0 1
# swap was on /dev/sda5 during installation
UUID=19f7f728-962f-413c-a637-2929450fbb09 none swap sw 0 0
If your fstab has things like /dev/sda1 instead of UUID it’s fine, but those entries are likely pointing to wrong devices. My current drive is /dev/sde instead of comments on fstab mentioning /dev/sda. With the live-image running you can get all the drives from the system running ‘lsblk’ and from there (or running ‘fdisk -l /dev/sdX’ as root, replace sdX with actual device) you can find out which partition should be mounted to what. Then run ‘blkid /dev/sdXN’ (again, replace sdXN with sda1 or whatever you have) and you’ll get UUID of that partition. Then edit fstab accordingly and reboot.
There’s a walkman model which is pretty much just that which runs some flavour of android but I don’t know who they think their customer base is as the pricing is absolutely stupid. Top of the line model has gold plating and a nice 4k price tag. Also it apparently has ‘oxygen free copper’ and other audiophile bullshit, but no FM tuner.
And then there’s a ton of similar products from China but no idea which models (if any) are actually useful.