It's an insane idea in a good way. I'm using hall sensors in other applications but I've never thought about their usage in switches like this. I wonder if this also eliminates bounce and therefore the need for debounce circuitry.
I think Wooting and other companies have similar offers. I am nevertheless excited about this one because Keychron does a very good job in offering polished but customizable products.
Looks cool as heck. I won't ever get this specifically because I need a 100% keyboard (love my Q6) for both productivity and gaming, but I am definitely interested in this technology.