The Unity3D version used in this article: 2021.3.6, Pico SDK 230, Pico OS v.5.7.1 Hardware Pico 4
Pico SDK can be downloaded from Pico official website.
Import SDK
Step 1: Create a Unity3D project
Step 2: Import PICO Unity Integration SDK
Select Windows > Package Manager.
In the Package Manager window, click + > Add package from disk.
Step 3: Upgrade XR Toolkit (I upgraded to 2.5.0 here and reported an error. I used 2.4.3)
Step 4: Import XR Toolkit resources
Project configuration
Step 1: Enable PICO XR plug-in
On the upper menu bar, select Edit > Project Settings.
In the Project Settings window, click the XR Plug-in Management > Android Settings icon.
Step 2: Set the package name and version number
Step 3: Complete other settings
Create an XR scene
Create a new Scene and delete the built-in ManiCamer
Add XR Origin (VR)
XR Origin (VR) object adds PXR_Manager script 
Configure the handle:
The left and right controllers distinguish and select the corresponding configuration.
Configure the handle model. Drag the Pico left and right handle model prefabs to the corresponding positions (gesture recognition can be ignored here)
Different models can be selected to display different handle models
Input Action Manager script adds configuration
You can see the handle model by publishing it directly.
Configure the hand model. Drag the left and right hand prefabricated models into the corresponding positions respectively.
pico equipment kiln opening gesture recognition
Run the program, put down the controller, and look at the back of your hands for a few seconds to identify your hands.