You are not alone, 8)
Same problem here.
Pico 3 Link.
Pico Link soft (latest 1.0.15) sees both, Steam and Device (PUI 4.7.1.5)
It connects to the device fine, but SteamVR (latest 1.22.13) can't detect the headset.

SteamVR (vrserver process) does load the pico add-ons and it appears to load and initialize the pico driver fine:
Sat Jun 18 2022 09:41:07.582 - Web language is english
Sat Jun 18 2022 09:41:07.582 - [Web] Starting web server on port 27062
Sat Jun 18 2022 09:41:07.618 - Connecting client (VR_ServerPipe_4472) app container status: 1
Sat Jun 18 2022 09:41:07.618 - New Connect message from C:\Program Files (x86)\Steam\steamapps\common\SteamVR\bin\win32\vrstartup.exe (VRApplication_Bootstrapper) (Args: ) 10216
Sat Jun 18 2022 09:41:07.624 - Creating Builtin AppInfo for C:\Program Files (x86)\Steam\steamapps\common\SteamVR\bin\win32\vrstartup.exe (VRApplication_Bootstrapper). steam.overlay.250820, , 10216
Sat Jun 18 2022 09:41:07.624 - AppInfoManager.ProcessConnected BEGIN 10216 C:\Program Files (x86)\Steam\steamapps\common\SteamVR\bin\win32\vrstartup.exe 7 steam.overlay.250820
Sat Jun 18 2022 09:41:07.629 - SetApplicationPid appkey=steam.overlay.250820 pid=10216, external transition
Sat Jun 18 2022 09:41:07.629 - SetApplicationPid: Setting app steam.overlay.250820 PID to 10216
Sat Jun 18 2022 09:41:07.629 - AppInfoManager.ProcessConnected END
Sat Jun 18 2022 09:41:07.629 - Enabling legacy input for steam.overlay.250820
Sat Jun 18 2022 09:41:07.638 - pico: driverpath C:\Program Files (x86)\Pico Link\driver\bin\win64\RVRPlugin.ini
Sat Jun 18 2022 09:41:07.641 - pico: controller type is 3
Sat Jun 18 2022 09:41:07.641 - pico: VEncdll C:\Program Files (x86)\Pico Link\driver\bin\win64\VEncPlugin.dll
Sat Jun 18 2022 09:41:07.642 - pico: GreateEnvcFunPtr success
Sat Jun 18 2022 09:41:07.642 - pico: mSetDstIpFunPtr success
Sat Jun 18 2022 09:41:07.642 - pico: SetPoseDepth success
Sat Jun 18 2022 09:41:07.642 - pico: mRegistLogFunPtr success
Sat Jun 18 2022 09:41:07.642 - pico: mRegistPushEncodedFramePtr success
Sat Jun 18 2022 09:41:07.642 - pico: VEncdll Load
Sat Jun 18 2022 09:41:07.714 - pico: driver_pico: Serial Number: Pico Neo 3
Sat Jun 18 2022 09:41:07.714 - pico: driver_pico: Model Number: Pico Neo 3
Sat Jun 18 2022 09:41:07.714 - pico: driver_pico: Render Target: 1920 1920
Sat Jun 18 2022 09:41:07.714 - pico: ______COMPOSITOR_INITIALIZE______
Sat Jun 18 2022 09:41:07.723 - AUDIO: Refreshing audio devices
Sat Jun 18 2022 09:41:07.723 - pico: right encode init success
Sat Jun 18 2022 09:41:07.724 - pico: go startup rtc device_id=0A-00-xx-00-00-xx
Sat Jun 18 2022 09:41:07.724 - pico: audioCaptureSession
Sat Jun 18 2022 09:41:07.724 - pico: DpHmdDriver::DpHmdDriver()
Sat Jun 18 2022 09:41:07.724 - pico: nvidai dp mode and amd dp mode all enable unsucessfully
Sat Jun 18 2022 09:41:07.724 - pico: dp::Init : window_width_=3664, window_height_=1920, window_x_=0, window_y_=0
Sat Jun 18 2022 09:41:07.724 - pico: dp: 1.200000
Sat Jun 18 2022 09:41:07.724 - pico: driver_pico: Serial Number: Pico Neo 3
Sat Jun 18 2022 09:41:07.724 - pico: driver_pico: Model Number: Pico Neo 3
Sat Jun 18 2022 09:41:07.724 - pico: driver_pico: Window: 0 0 3664 1920
Sat Jun 18 2022 09:41:07.724 - pico: driver_pico: Render Target: 2198 2304, fScale: 1.200000
Sat Jun 18 2022 09:41:07.724 - pico: driver_pico: Seconds from Vsync to Photons: 0.000000
Sat Jun 18 2022 09:41:07.724 - pico: driver_pico: Display Frequency: 72.000000
Sat Jun 18 2022 09:41:07.724 - pico: driver_pico: IPD: 0.063400
Sat Jun 18 2022 09:41:07.724 - pico: socketport:29722
Sat Jun 18 2022 09:41:07.724 - pico: socketport:29722
Sat Jun 18 2022 09:41:07.724 - pico: hidobj OpenHidDevice ok
Sat Jun 18 2022 09:41:07.724 - pico: socketport:29732
Sat Jun 18 2022 09:41:07.725 - pico: socketport:29732
Sat Jun 18 2022 09:41:07.725 - pico: socketport:29734
Sat Jun 18 2022 09:41:07.725 - pico: socketport:29734
Sat Jun 18 2022 09:41:07.725 - driver pico implements interfaces IVRSettings_003 ITrackedDeviceServerDriver_005 IVRDisplayComponent_002 IVRDriverDirectModeComponent_007 IVRCameraComponent_003 IServerTrackedDeviceProvider_004 IVRWatchdogProvider_001 IVRVirtualDisplay_002 IVRDriverManager_001 IVRResources_001 IVRCompositorPluginProvider_001
Sat Jun 18 2022 09:41:07.725 - Loaded server driver pico (IServerTrackedDeviceProvider_004) from C:\Program Files (x86)\Pico Link\driver\bin\win64\driver_pico.dll
...
the "- pico:" entries came from the pico dll.
Eventually it fails with a "VRInitErrorInitHmdNotFound"
...
Sat Jun 18 2022 09:53:56.599 - Allowing driver load failure VRInitError_Init_HmdNotFound for application vrwebhelper_main (3100) because it is VRApplication_WebHelper
Sat Jun 18 2022 09:53:56.599 - Processing message VRMsg_Connect from vrwebhelper_main (3100) took 0.00833 seconds
...
vrmonitor (vrmonitor.exe process) shows a "Reading EDID vendor Id time out:
Sat Jun 18 2022 10:26:42.413 - vrmonitor.exe 1.22.13 startup with PID=9832, config=C:\Program Files (x86)\Steam\config, runtime=C:\Program Files (x86)\Steam\steamapps\common\SteamVR
Sat Jun 18 2022 10:26:42.413 - vrclient type=VRApplication_VRMonitor
Sat Jun 18 2022 10:26:42.414 - [Settings] Load Default Json Settings from C:\Program Files (x86)\Pico Link\driver\resources\settings\default.vrsettings
Sat Jun 18 2022 10:26:42.414 - [Settings] Load Default Json Settings from C:\Program Files (x86)\Steam\steamapps\common\SteamVR\resources\settings\default.vrsettings
Sat Jun 18 2022 10:26:42.414 - [Settings] Load Json Settings from C:\Program Files (x86)\Steam\config\steamvr.vrsettings
Sat Jun 18 2022 10:26:42.418 - WaitNamedPipe SteamVR_Namespace failed because no one is listening at that name.
Sat Jun 18 2022 10:26:42.418 - Starting vrserver process: C:\Program Files (x86)\Steam\steamapps\common\SteamVR\bin\win64\vrserver.exe
Sat Jun 18 2022 10:26:42.421 - WaitNamedPipe SteamVR_Namespace failed because no one is listening at that name.
Sat Jun 18 2022 10:26:42.421 - CSharedResourceNamespaceClient::Init(): failed connect
Sat Jun 18 2022 10:26:42.421 - CSharedResourceNamespaceClient::Init(): still waiting for vrserver to reply with namespace data
Sat Jun 18 2022 10:26:42.521 - Client (SteamVR_Namespace) app container state: 1
Sat Jun 18 2022 10:26:42.522 - CSharedResourceNamespaceClient::Init(): received namespace data 2336
Sat Jun 18 2022 10:26:42.522 - WaitNamedPipe VR_ServerPipe_2336 failed because no one is listening at that name.
Sat Jun 18 2022 10:26:42.623 - Client (VR_ServerPipe_2336) app container state: 1
Sat Jun 18 2022 10:26:42.707 - Received success response from vrserver connect
Sat Jun 18 2022 10:26:44.817 - Timed out waiting for a good app key
Sat Jun 18 2022 10:26:44.817 - App key after connect message:steam.overlay.250820
Sat Jun 18 2022 10:26:44.823 - Reading EDID vendor Id timed out.
Sat Jun 18 2022 10:26:44.824 - Started C:\Program Files (x86)\Steam\steamapps\common\SteamVR\bin\vrwebhelper\win64\vrwebhelper.exe with pid 12684
Sat Jun 18 2022 10:26:44.849 - Failed to load binding file. We'll wait and try again when CRC or load count changes( computed CRC=0, old CRC=0, shared CRC=0, load count=0, shared load count=1
Sat Jun 18 2022 10:26:44.850 - Unable to create property container PC_100000000 because creation was not requested
Sat Jun 18 2022 10:29:03.990 - VR_Shutdown called
not sure how the process are interlinked, but vrmonitor.exe is the one loading the pico driver dll.
I tried reinstalling Steam, SteamVR and Pico Link but so far no much luck.
This is ofver Wifi, haven't tried DP yet, but I doubt it will work. There is a:
" pico: nvidai dp mode and amd dp mode all enable unsucessfully"
in the vrserver log, but I guess that is just because I'm trying Wireless"
My take is that the vrmonitor.exe (pico driver) is not "talking" with the "pico link.exe" process