I am having trouble typing pipe characters in GLISH. How do I fix this?

I understand your frustration with this. I do not know what the exact cause of this issue is and I am unable to reproduce it, but have encountered it previously. I installed a fresh installation of Debian 9 on a new Linode and can verify that typing these characters work. So, for reference. here are all the settings that I think may be pertinent:

Environment Settings

TERM="linux"
LANG=en_US,UTF-8
SHELL=/bin/bash

Keyboard Layout

dpkg-reconfigure keyboard-configuration

 -> Generic 105-key (Intl) PC 
-> English(US) 
-> AltGr = "The default for the keyboard layout"
-> Compose key = "No compose key"

Once you have run this, you will need to restart the service:

sudo systemctl restart keyboard-setup

Grub Settings

My /etc/default/grub file looks like:

# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
#   info -f grub -n 'Simple configuration'

GRUB_DEFAULT=0
GRUB_TIMEOUT=10
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT=""
GRUB_CMDLINE_LINUX="console=ttyS0,19200n8 net.ifnames=0"

# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
#GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"

# Uncomment to disable graphical terminal (grub-pc only)
#GRUB_TERMINAL=console

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
#GRUB_GFXMODE=640x480

# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
GRUB_DISABLE_LINUX_UUID=true

# Uncomment to disable generation of recovery mode menu entries
#GRUB_DISABLE_RECOVERY="true"

# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"

# Enable serial console for LISH
GRUB_GFXPAYLOAD_LINUX=text
GRUB_TERMINAL=serial
GRUB_SERIAL_COMMAND="serial --speed=19200 --unit=0 --word=8 --parity=no --stop=1"

Client Operating System, Browser, Version, and Keyboard Settings

macOS Catalina
Version 10.15.1
Keyboard Layout: U.S.
Keyboard Type: Character to Right of Left Shift is 'Z', Character to the Left of Right Shift is '/', Set to ANSI (United States and others).

Typing these characters in GLISH works for both a MacBook Pro keyboard and an external 87 Key Keyboard.

Browser: Google Chrome Version 78.0.3904.70 (Official Build) (64-bit)

Please let us know if this helps you identify the issue or rule out sources of the problem. If you find out the cause of the problem, we would love to know what you found out.