The first thing to do is ignore the tutorial. You do not need to create a new user, but you definitely do need to change the default password.
As far as "undoing" the command, you need to login to your Pi from the new account the tutorial writer had you create, and re-set the password for user pi. Once you're logged in as the other user (and ...
There's nothing wrong with your approach for individual text files. For a binary file (or a large number of files/directories which you'd pack together with tar/gzip), you can use base64 to encode them as text:
Receiver (Pi over picocom):
cat | base64 -di > file
Sender (another terminal on the PC):
cat file | base64 > /proc/`pidof picocom`/fd/0
I'm not familiar with "Blink" but presume this is not a limitation of that.
After logging in and before you start emacs try:
The first one is necessary for the second one to work, which should set 24-bit (aka "true color") depth if possible.
I'm not an emacs user either; if this does ...
Of course there are better solutions for troubleshooting instead of following four (outdated?) tutorials. One of it is to use a Linux box instead of a MS Windows computer. You can just boot a live CD of one of the popular Distributions like Debian, Ubuntu or what you like. I would prefer Debian because the Raspberry Pi OS is a flavor of Debian. Now you can ...
You can put a wpa_supplicant.conf in the boot partition, and it will overwrite any existing.
You can configure wpa_supplicant.conf for multiple networks.
See How to set up networking/WiFi
There is NO WAY to change interfaces, but then there is NO REASON to ever modify it.
Just delete it - effectively on Stretch and Buster it does NOTHING.
NOTE that tutorial ...
EDIT: This only seemed to fix the problem temporarily!
FOUND THE SOLUTION!
It seems it was an issue with the router.
My DHCP IP range was set to be 10.0.1.100-10.0.1.200.
This seemed to cause an issue with how the router handled the traffic between devices and would drop connections.
I set the DHCP range to 10.0.1.2-10.0.1.202 and it seems to work fine now....
Occasionally caching prevents Zero-conf resolution and the only cure I have found is to restart all network devices although pinging sometimes refreshes the arp cache.
You may be interested in the following script I use.
This falls back to a reserved IP Address if Zero-conf fails.
# script to start ssh connection to Pi
# If not found use default ...
EDIT: Apologies - I mis-read your question, and what follows is a revised answer. It also turns out that a full answer to your question is a bit more complicated than I thought initially. I'm going to leave this answer here, although it's probably less an answer than a guide for further reading. Please let us know if you have further questions.
The Pi Zero ...
You need a computer with which you can read and write to the SD root filesystem (the second partition in Raspbian/RpiOS) for what I am suggesting.
Read this about how to disable the root password. This would allow you to login root and make whatever changes, such as passwd --unlock pi.
Create new file called "ssh" in /boot/
Connect wire internet from you PC to your Rasp, start your raspberry.
Use cmd or putty or any other SSH apps. The IP address to the you Rasp will be "raspberrypi". Your default username is "pi" and your efault password is "raspberry"
For example, if you use cmd: "ssh pi@...
If you are looking to get access to the Pi with a floating IP (due to 3G dongle), I see two good options.
As ElefantPhace commented, Use ddns of some sort to create a statically available Domain name. This solution may not work if the 3G hotspot acts as a router and doesnt have port forwarding.
Run an OpenVPN server instance on your AWS Server and Connect ...
Although old fashioned, Picocom supports filetransfer, x-modem, y-modem, z-modem and ascii-xfr. If I where you, i'd go for z-modem. The package you are looking for is lrzsz (and notzmodem as I stated earlier). Note that it operates a bit different from scp.
I was able to get this working. After following the instructions from the Emacs FAQ, I found that I had to run export TERM=xterm-24bits (note the plural ‘bits’) and that enabled 24-bit color when running $ emacs.
If anyone is interested in getting 24-bit color to work over Mosh, you’ll need to build from scratch as described here.