Remapping Keys for Xorg Xmodmap

# xev
# xinput test /dev/wskbd
# xmodmap -pke

.Xmodmap contents
# Use WIN key as Escape Key
keycode 115 = Escape NoSymbol

# Assign Escape Key for Back Tick and Tilde
keycode 9 = grave asciitilde

In .xinitrc
xmodmap ~/.Xmodmap

--- Notes---
keycode nn = a b c d e f
a = key press
b = key + shift
c = key + mode_switch
d = key + mode_switch + shift
e = key + iso_level3_shift
f = key + shift + iso_level3_shift
nosymbol = ignore

You mostly need the first two settings (ordinary key press and key + shift)

keycode 51 = backslash bar backslash bar
keycode 9 = grave asciitilde grave asciitilde
keycode 11 = apostrophe at apostrophe at dead_circumflex dead_caron dead_circumflex
keycode 48 = 2 quotedbl 2 quotedbl twosuperior oneeighth twosuperior

https://unix.stackexchange.com/questions/429835/advanced-key-mappings-in-linux