Probably using a QMK firmware-based keyboard where you can access different layers and shortcuts.
I'm using one right now (though mine runs off ZMK which is similar but wireless) which is a split with just 42 keys. The rest--numbers, symbols, function keys, etc. are all under layers. The layout is dynamic because holding down different keys makes the layout 'change' as you do so. Holding down the left spacebar and pressing 'Z' sends 'F1' to the computer while holding down another key on the right half turns my WER/SDF/XCV keys into a Numpad, etc.
Yes, both keys send the same key code to the computer, however, pabloescobyte said they’re using ZMK, so the left/right space bar distinction is happening on the level of the keyboard controller.
I'm using one right now (though mine runs off ZMK which is similar but wireless) which is a split with just 42 keys. The rest--numbers, symbols, function keys, etc. are all under layers. The layout is dynamic because holding down different keys makes the layout 'change' as you do so. Holding down the left spacebar and pressing 'Z' sends 'F1' to the computer while holding down another key on the right half turns my WER/SDF/XCV keys into a Numpad, etc.