Well, the irc chat was very prommissing.

by default, there are 12 key-combos the user can configure as hotkeys to launch any application that has .desktop file, and you can invoke call over dbus/scripting, so just make .desktop file containing/starting that script.

This would enable voicemail, ICE, browser, email, etc buttons without programming.

With programming you can make some OS/wayland/some layer grab the keys, and all things related to keyboard are possible.

So macro record/playback should be possible.
Long-presses should be possible.

It should be possible to have a popup, so pressing the ICE button could popup a dialog where you can select the desired contact to call.

Locking the screen rotation is certainly possible (the screen is locked in landscape while the keyboard is open) although not all apps have a landscape layout.

Nice nice nice. I'll be adding many keys to my layout