Thank you Andrew for this information.
I set it to true cause the builder was asking for a Depex section.
Setting it to false allows QEMU to boot properly.
Nonetheless, the driver doesn't seem to be called... yet.

Concerning Pedro's suggestion (Olá!!!), thank you for pointing me to the DebugLib, I'll look into it. 
Nonetheless, I'll need to use ConInt and ConOut in production.
I am aware of a DXE program that does it. Maybe I was passed the wrong information and the program is running on another phase...
Anyhow, in theory I'd be able to install the I/O protocols in the DXE phase in order to be able to use them. Right?
The TerminalDxe.inf, a UEFI driver, states: Terminal module installs Simple Text Input(ex)/Out protocols for serial devices

I think assumed erroneously that the OvmfX64.fdf is setting the ordering of the DXE drivers.
After Andrew's answer I realised that may actually be done in the Depex Section?
I'll read its specification now in order to better understand how to use it. 

Nonetheless, I tried turning it from a DXE_DRIVER into a UEFI_DRIVER and it's still not natively being listed in EFI Shell's drivers command.
I don't see yet how mine differs from TerminalDxe. Maybe it's crashing and being unloaded.

Maybe it's simpler than all of this. 
My true goal is: my program needs to be shipped with the BIOS image in ROM and run for sure on every boot, with no possibility of being circumvented.
I have also read that some DXE drivers are not guaranteed to run if something like fast boot is activated.
Taking that in consideration, what module type should I create to achieve my goal?

Finally, is there any documentation on actual programming using EDK2?
Say, which functions can I use to read user input?
Or what dependencies do I have to include as LibraryClasses if I want to use a certain function?
Is reading source code the only way to go?
I have also used DoxyGen to generate docs, but it's far from ideal.

Cheers,
Diogo