Interesting -- integrated LEDs. Not possible with tactile or clicky ALPS switches due to lack of space.
The new Matias Quiet Pro has integrated LEDs in a tactile switch, and the transparent switch shells suggest possibly the LED is below the switch instead of integrated – will have to see when someone does a proper review. I won't be getting mine until next year (ISO model).
The Tactile Pro 3 uses XM greens for the lock keys, with integrated LEDs, and I'm wondering now whether greens were always designed with LED integration in mind, rather than being something added by XM.