Desperate measures - erased all discs

If you examine the screenshot in Step 2 of How to erase a disk for Mac, you will see something similar to what you're seeing on your Mac.

Whatever appears below APPLE SSD TS128E Media does not matter. Select that device, and erase it. That will erase everything below it. Just be sure to Start up from macOS Recovery as described in Step 1.

Follow all those steps. Step 1 through Step 7.

You didn't erase too much, in fact you're doing it right because erasing a Mac requires following What to do before you sell, give away, or trade in your - Apple Support. You already arrived at its last step, and you can even give it to your friend the way it is.

Not a big deal.

First, start up from macOS Recovery and follow these instructions to erase the startup disk: How to erase a disk for Mac. You will be following the first set of instructions—those under "How to erase your disk".

For Step 3, choose Mac OS Extended (Journaled).

After it finishes erasing the disk, quit Disk Utility which returns to the macOS Utilities window. Then, Reinstall macOS.

No worries. You did everything right. It's far more common for someone to give away (or buy, or sell) a Mac that has not been properly prepared for its new owner. That's a much bigger problem and it leads to anger and frustration for both parties.