Changed Home Directory in Users & Groups advanced settings to / instead of Users/username

You can try using these instructions to run setup assistant again which can create a new admin user account:

Restarting Setup Assistant to create Admin user - Apple Community

If you can create a new admin account, you could use that account to fix your other account's home folder.

In the future if you are play with this level of advanced user games, you should ALWAYS have a fresh full backup of your system you can restore from.

And already having a backup admin account is always useful.

And playing on a spare system you can sacrifice is even safer, because you can wipe it and start from scratch with only some wait time, but no loss of valuable data.

You can use the 'find' command from Terminal to search for things. It does not need you to change your home folder.

Here's what Apple has to say about that: Change the name of your macOS user account and home folder - Apple Support. Note the warning.

At this point you can try a reinstall of macOS: Reinstall macOS - Apple Support

Or as a last resort: Create a bootable installer for macOS - Apple Support

I have no idea if a restore from Time Machine will rectify the situation, but if you can login you can try: Restore your Mac from a backup - Apple Support

If you can't login, you can't create a new user.