Can it be used like a kettle - ie can it rapidly heat up a quart of water without a coffee residue taste? No, it cannot.

Just because they both heat water doesn’t make them similar.

Pretty much. I used my keurig this way for a few years until i realized I'm really not using pods and am only using it for hot water to make tea (via normal steeping). If you brew coffee and then use it for something right after I don't recall there being much coffee taste, but you could probably run a small cup setting to flush things in the pod area a bit if needed.

I've since switched to a Zojirushi water boiler which I adore, especially after learning my keurig wasn't getting hot enough to really brew the tea well.

I used to use my Senseo to make ramen so ¯\_(ツ)_/¯

I strongly disagree. With a kettle, the whole volume of water is being heated at once and is a uniform temperature. A Keurig or drip coffee maker is only heating a small volume of water at a time. By the time you process a whole liter of water the first bit will have already cooled off a lot. It's a very different process and potentially a very different outcome.

If you're making a single cup (~250mL) why do you need to heat 1000mL of water?