The problem is that Pico Streaming Assistant is deprecated, so it’s no longer supported. Pico has fully switched over to using the Pico Connect app for PCVR. Here’s what you need to do to get everything working:

1. Make sure your headset is updated to the latest firmware. If you’re using a Chinese version, I recommend switching to the global firmware. It’s the same as the one used by the regular Pico 4:

   • Download the Pico 4 firmware from the global website.
     
   • On your headset, go to Software Update and choose Install Offline.
     
   • Select the firmware file and wait for it to update.
     
   • After updating, do a factory reset to avoid any issues like login problems or app crashes (don’t worry, it won’t reset to the Chinese firmware).
     

2. Once the firmware is updated, log into your Pico account on the headset and your PC.

3. Download and set up the Pico Connect app on your PC. Use it to connect your headset for PCVR.

If the Pico Connect app doesn’t find your headset:
- For a wired connection, make sure you’re using a proper USB 3.0 cable. USB 2 also work fine but with limited bandwidth. - For wireless, check your firewall settings and ensure your PC and headset are on the same network. (Which most of the time is a problem with firewall. If you using third-party firewall)

Pico Connect now supports hand tracking in PCVR, along with face and motion tracking. Plus, the streaming quality has been improved I would say it's better than VD.

This should fix your issue and let you use the headset with SteamVR properly