I see I downloaded some .iso files, for x84_64 at least, but also some aarch64, 2 years ago. A decade ago with slow internet, I focused on as small as possible, so the NET variant is smallest.
Now did a refresh and it is:
openSUSE-Tumbleweed-NET-x86_64-Snapshot20260815-Media.iso
The confusion mentioned earlier comes from the fact that I did not manage to use the Rescue .iso as what its name suggests. Instead I made a ‘Live’ system with it that uses an extra storage (8GB or so) for storage changes, it uses overlayFS. Just for seeing what new/fresh/minimal Tumbleweed looks like.
For ‘rescue’ in this topic, the trick is to use the normal installer .iso and start installation process until you need a first decision, e.g. accept terms or somewhere which DE to use. Then abort and the screen then goes into text mode (linuxrc 9.6, kernel 7.1.8 ATM).
Then in [Main Menu] select [Start Installation], then in that sub-menu [Start Installation], select [Boot Installed System]. The tool then searches all storage for a rootfs, might be multiple OSses and Btrfs subvolumes. For my current test on a VM with just a virtio vda2 rootfs and the .iso from USB, it is 1 line. Further search result options are then done to help you get the correct kernel cmdline. Then it starts that rootfs.
I use Tumbleweed with all initial Btrfs subvols removed and a manually set default subvol to keep it as simple as possible and in line with other distros/filesystems and architectures (other non-UEFI bootloaders especially), but if the fstab on the rootfs is not messed up, it should also be straight-forward I think.
If things on the rootfs are messed up, you indeed might select Rescue in the sub-menu or just use the Rescue .iso to get an parallel Linux system for doing all sorts of surgery on the broken/corrupted/non-booting system on the computer’s main storage. Another option might be to select Upgrade, but is many years ( a decade or so) ago I used that, it will overwrite/reset quite some preferences I think.
If initrd is the problem, or you want to clone/port to another computer with UUID of rootfs different (must be for Btrfs if same name-space (same computer), I once took the vmlinuz and initrd from the Rescue .iso as that has no fixed embedded UUID. I am sure there are dracut options to make it more flexible, but haven’t found those. It is much easier in Debian as the root= statement on the cmdline overrides things, but also that is just defaults, might be different if more customization has been done, e.g. LVMroot and/or cryptroot.