Because then things like holding shift on one half and a letter on the other wouldn’t work.

Because this allows you to keep the halves further apart, which is considered more ergonomical.

Typically, each half can, in fact, be used independently (they each have their own microcontroller).

That looks absolutely stunning, great job! Really futuristic and clean!

Looks real nice, good job on getting it out there!

…but I want to avoid Discord, too…

There’s docker-mailserver which runs the entire stack in one container.

Pedantic side-note: you don’t run “a docker”. You run a container, and you happen to use docker to do so. Just like you don’t send someone an Outlook or Chrome their website. Docker is just a way of running OCI containers, not the whole tech.