Typically in a 5v system you'd treat capacitor output voltages under 2.3V as pressed and over 2.3V as released. There is a "pullup" resistor and the switch is wired to "pull down" the circuit towards ground, through the mentioned resistor.

Most Microcontrollers have the pullup resistor built in. Modern ones even let you turn the pull-up feature on and off per pin with a SFR (a special register /fixed memory address you can write to where you change hardware settings). Often you can also choose between reading a pin or driving it as an output.

The most important thing to know about debouncing is that any hardware switch bounces from 50-200 times over a very very short interval when you press it. You can use an oscilloscope to see that. The bouncing is not as bad on release but I imagine it still exists there too.

Another fun hardware trick is that when you turn off a magnet (like a relay) you can get a massive over-voltage pulse back (10x typical drive) for a moment. You need to protect yourself from that, for instance with a Schottky diode. Here's a discussion on that fun detail [1].

[1] https://forum.allaboutcircuits.com/threads/reduce-voltage-sp...

Of course. Hardware debouncing came long before software. It's basic electronics. Many switches have it built in.