It's the onscreen keyboard built into the iPad. With Universal Control, you should be able to use that keyboard as an input device to the Mac; or with SideCar move the Mac screen to the iPad but then the keys will cover part of the screen.
There also some remote apps that may let you use the iPhone keyboard as well. Th eApp Store has a bunch of choices.
I think the closest you're gonna get is something that uses a touch screen. Microsoft made "touch covers" for the original Surface Pro but those are long since obsolete and everything has movement now. iPad is an option as others stated but you could also look at Windows tablets, like the Surface and if money is no object something like the Thinkpad X1 Fold which would let you get a laptop-esque form factor while typing on the screen: