I want to create an application that recognizes it as a usb keyboard in Windows programming.

USB is an asymmetric system that is completely different from Host and Function. PCs are, in principle, hosts, so you have more to think of as trying to play the role of a keyboard (=Function).In other words, the prerequisite knowledge required increases at once = technical difficulties increase.It's a bit too high (too high) to try.

Furthermore, the less technical but high barrier is that today's Windows 10 x64 (64-bit windows) requires a digital signature (=to be purchased, or paid for), making it difficult to develop a practical driver at an individual level.

If you want something to act as a keyboard from the perspective of the PS4, the Oira will actually create a USB Function device that acts as a keyboard.So the device accepts control from the PC, i.e., what is not a keyboard from the PC?However, once implemented as an HID, the device driver development I mentioned earlier is no longer necessary, so it is a little easier. To create devices that act as USB functions from both the PC and PS4, you can only use USB using a microcomputer with two USB functions, and if you have only one system, you will be able to use COM: ports to accept control from your PC.

It's possible to build a physical device only with knowledge of that physical device, but if you try to simulate it with something else (in this case, a PC), you'll need another knowledge and it's even more difficult.Just know that you're willing to do something technically expensive (if you're an Oira, I'll do it if it's a job, but if it's a hobby, I won't touch it)

As a result, Windows programming is also possible depending on your efforts.

At least driver development is required if the device, whether virtual, is running on a PC.
If you want the PS4 to recognize it as a keyboard, you can implement a virtual keyboard using USBTypeC.
I think it's a kind of Windows programming, but you should recognize it as a completely different world.
The mainstream method is implemented using a framework called KMDF or UMDF.The language used is C/C++ (although it may have improved recently).
I'm sorry, but I don't know how to implement USBTypeC.

Driver development is quite dark.It is easy to load without any blogs to tell you.The documentation is not very good, so if you're serious about it, you'll have to be prepared.

Note:
UMDF: https://docs.microsoft.com/ja-jp/windows-hardware/drivers/wdf/advantages-of-writing-umdf-drivers
USBTypeC: https://docs.microsoft.com/ja-jp/previous-versions/windows/hardware/drivers/mt805826(v=vs.85)