Ubuntu – How to config hotkeys for switching between consoles in ubuntu

After a lot of attempts to fix this various ways, I finally figured out how to use dumpkeys and loadkeys to modify the kernel's "keyboard translation table". Here are the loadkeys strings to set RightAlt+F1 through RightAlt+F12 to their respective offsets from tty12:

altgr   keycode  59 = Console_13
altgr   keycode  60 = Console_14
altgr   keycode  61 = Console_15
altgr   keycode  62 = Console_16
altgr   keycode  63 = Console_17
altgr   keycode  64 = Console_18
altgr   keycode  65 = Console_19
altgr   keycode  66 = Console_20
altgr   keycode  67 = Console_21
altgr   keycode  68 = Console_22
altgr   keycode  87 = Console_23
altgr   keycode  88 = Console_24

Why Ubuntu doesn't include this in the default setup remains a mystery. :)

Credit for the answer goes to DK Bose who linked the answer by none other than Alan Pope here: https://askubuntu.com/a/929115/248158. But for completeness, I'm putting the answer here as well. The keyboard was set to unicode mode, and by setting it to raw mode, these key sequences were then interpreted as expected.

sudo kbd_mode -s

This is persistent across reboots. And to restore it to how it was before:

sudo kbd_mode -u