Here is a simple script that can show you the hotkeys bound in ~/.config/i3/config :

#!/bin/bash - 
#===============================================================================
#
#          FILE: i3-showkeys.sh
# 
#         USAGE: ./i3-showkeys.sh 
# 
#   DESCRIPTION: 
# 
#       OPTIONS: ---
#  REQUIREMENTS: ---
#          BUGS: ---
#         NOTES: ---
#        AUTHOR: Amit Agarwal (aka)
#  ORGANIZATION: Individual
#       CREATED: 11/26/2019 14:22
# Last modified: Tue Nov 26, 2019  02:43PM
#      REVISION:  ---
#===============================================================================

set -o nounset                              # Treat unset variables as an error


> /tmp/keys
cd ~/.config/i3
grep '^bindsym $mod' config|grep -v '^#'|grep -v 'move container to'|grep -v 'workspace $ws'|sed 's/bindsym //'|grep -v '='|while read key line
do
    printf "%20s\t?\t%s\n" "$key" "$line"  >> /tmp/keys
done

xterm -e "cat /tmp/keys; read -p 'press any key to continue'"
rm -f /tmp/keys

And once this is done, you can bind the script in i3 config like this:

bindsym $mod+Shift+h exec ~/bin/i3-showkeys.sh

Restart i3. And then you can press “Mod key + Shift + h” at any time to see all the bindings in your config.