The weird text the main bird is rattling off it something called "Assembly". Many programming languages don't really tell the computer what to do, they more or less outline the behavior they want, and then another program called a compiler turns that into 1s and 0s that a computer can actually understand. If you've ever heard of binary, that's what these 1s and 0s are. Assembly is one level of abstraction* above the 1s and 0s. It is a good way for humans to understand what a computer is actually doing without having to look at the original programming code, and without 1s and 0s. So the main bird represents a computer doing it's thing, running some program.

Then comes the crow with a "Hello It's me. The Keyboard! Someone pressed the letter e." The crow represents something called an interrupt, which is exactly what it sounds like. It interrupts the normal flow of a program to signal to a computer "Hey, you need to deal with this. Like, now."

The reason why he is a keyboard is because that is how old keyboards used to work. Before USB ruled the world, mice and keyboards used something called a PS2 port. If you ever saw an old mouse or keyboard with a green or purple plug on one end instead of a USB, then that's the old style we are talking about.

Modern USB keyboards are a little more polite and will wait in a line until the computer is ready to deal with whatever the human just typed, but old PS2 keyboards used interrupts to demand attention. This was really important for old slow computers that needed to respond to user input ASAP. Modern computers can handle that sort of thing a little bit better.

I think that is enough context to understand the meme.

*Not really: see ISA layer and micro-ops for more information

https://www.youtube.com/watch?v=CVarSJQzw38

Nemo πs me keyboard?

I remember laughing at this meme and now I turn my nose up at 6-7

Modern CPUs can manage what interrupts them. Almost nothing actually does.

Computers have a CPU just to get in the way of things interrupting the main CPU.

If you want a USB host controller to interrupt your CPU, I can recommend some nice embedded SoCs

So if i created my own keyboard from scratch on a open hardware microcontroller, could i implement this?

The USB controller that interrupts the CPU lives on the other side of the connection, so you'd just be building hardware that responses to the polling. If you're curious what that looks like, Ben Eater has a cool video looking at what that looks like for a USB 2 keyboard https://youtu.be/wdgULBpRoXk

There’s also the case of Bluetooth dongle keyboards not working in UEFI (except that one) but USB always do. Is it this or just the UEFI not having drivers?

I am no USB Keyboard expert, but through the power of looking it up it seems like most of these do not operate as a HID (human interface device, like mouse and keyboard) so need driver support, but some start up with a basic HID proxy which might be you have one that works. From an older thread about BIOSes rather than UEIFs

A keyboard using Bluetooth cannot access the BIOS. Logitech Bluetooth keyboards get around this by having a dongle that pairs with the keyboard in a more basic, non-Bluetooth mode until the driver kicks in and switches modes. Microsoft might be similar mode with their keyboards and dongles, but I cannot confirm that.

https://superuser.com/questions/242457/use-a-bluetooth-keyboard-to-access-edit-the-bios