Accidentally deleted /home on an ext4 SSD—what is the safest recovery approach?

Because this is an NVMe SSD, recovery may be impossible even though the deletion was recent. SSD firmware and the operating system can use TRIM/discard to mark the blocks as available, after which the old contents may no longer be readable. Do not boot the installed Debian system again, reinstall to that partition, or save recovered files there. Recover files only to a separate disk, and expect filenames, permissions, and directory structure to be incomplete if recovery succeeds.

If the files are not recoverable, you can at least recreate the account's home directory after reinstalling or repairing Debian: create `/home/username`, assign it to the user and their primary group, and restore the needed configuration and data from any backups. For the future, use backups or snapshots, and consider safer deletion tools and more explicit commands when working around important system directories. A backup system such as Borg can make this kind of mistake much less painful.

Stop using the NVMe drive immediately and avoid mounting the partition, even read-only if possible. Boot the live USB, identify the device carefully, and create a sector-by-sector image or clone onto another drive using a tool such as GNU ddrescue. Perform all recovery attempts on that image, not the original disk. For ext4, tools such as TestDisk or specialized recovery software may find directory entries, but the results depend heavily on whether the filesystem has already issued discard/TRIM commands. If the data is important, the safest option is to preserve the drive and consult a professional recovery service rather than repeatedly experimenting.