Find input devices.

InputDeviceHelper.cs

using System.Diagnostics;
using System.Runtime.InteropServices;

internal static class InputDeviceHelper
{
    [DllImport("User32", SetLastError = true)]
    private static extern uint GetRawInputDeviceList(
        [Out] RAWINPUTDEVICELIST[]? pRawInputDeviceList,
        ref uint puiNumDevices,
        uint cbSize);

    [StructLayout(LayoutKind.Sequential)]
    private struct RAWINPUTDEVICELIST
    {
        public IntPtr hDevice;
        public DeviceType dwType;
    }

    public enum DeviceType : uint
    {
        /// <summary>
        /// The device is a mouse.
        /// </summary>
        RIM_TYPEMOUSE = 0,

        /// <summary>
        /// The device is a keyboard.
        /// </summary>
        RIM_TYPEKEYBOARD = 1,

        /// <summary>
        /// The device is an HID that is not a keyboard and not a mouse.
        /// </summary>
        RIM_TYPEHID = 2
    }

    public static void FindDevices()
    {
        uint deviceListCount = 0;
        uint rawInputDeviceListSize = (uint)Marshal.SizeOf<RAWINPUTDEVICELIST>();

        if (GetRawInputDeviceList(
            null,
            ref deviceListCount,
            rawInputDeviceListSize) == 0)
        {
            var devices = new RAWINPUTDEVICELIST[deviceListCount];

            if (GetRawInputDeviceList(
                devices,
                ref deviceListCount,
                rawInputDeviceListSize) == deviceListCount)
            {
                foreach (var device in devices)
                {
                    Trace.WriteLine($"Handle: {device.hDevice} Type: {device.dwType}");
                }
            }
        }
    }
}