To be clear, in the US the "instant hot" tap (when present) is separate from the main adjustable-temperature faucet. It's normally off to the side and visually distinct. It's usually much smaller and provides a limited amount of water from a pre-heated tank under the sink.

American here... I've never in my life seen one of these. I'm sure they exist, but they're not common.

They’re a somewhat common upgrade in high-end houses. You can install one yourself relatively easily assuming the sink has a hole for it.

I’ve only seen one in person myself. More common is a fridge that can dispense hot water (!!)

It’s definitely a “high-end” kitchen feature, I agree that’s it’s not standard in most homes.

Zero. The 195F tap is not the same one you use for normal hot & cold water. The normal hot water in our house is set to 140F (we do not have any small children or elderly, if we did I might dial it down to 120F).

Fair enough, my girlfriend is mad when I use the hot water and later she suddenly "burns" her hand with ~50/60°C water :)