Arduino Leonardo as USB Keyboard with WiFi module
Its always very unlikely that someone will have done exactly the same project as you, which is why you need to break it down.


You want to talk to an Arduino over Wifi.
You want he PC to send commands to the Arduino.
You want to make the Arduino act as a keyboard.


I know each of those three parts in on this site, so that should help answer a lot of questions on how to do it, but obviously some of the solutions may conflict so you'll have to discard them.


You can use an ESP8226 - the Arduino talks to it via serial (software serial).
You will need an application (c# will be easiest for Windows) that will send data to the Arduino.  You need to design and implement a protocol, using REST may be a good idea.
I've never done it and don't know how, but I think I read there is a HID Library (Human Interface Device aka Keyboard or rat) and that makes thinks easier.


As to what hardware you could use there may well be performance constraints, that affect what hardware you can use.  I suspect the lower spec Arduiano's may introduce a lag that may not be acceptable.  Since you want to do it over Wi-Fi, you might want to have a look at the ESP8226, which can be programmed like an Arduino and has native Wi-Fi.  I'm not sure if you can use it as a HID though.