>>105858154
>Umbrella keycaps
They exist. You can get and 3d print type writer style key switches for Model Ms that are without a skirt iirc. For MX there is Lamé and FunkMonk which are both 3d printable low profile caps with little to no skirt
>Chime switches
Not a thing (yet) and the size required for feelable resonance wouldn't make them practical. However, there are buzzer/haptic systems you can add with QMK firmware compatible keyboards that can make the board vibrate in response to keys registering. Same sort of system as piston actuators like with beamsprings