My pc don't cover the min spec ??? with RTX 4050

The best way to play HalfLife Alyx is to have Meta Quest Link set as your default OpenXR runtime, but actually connect your headset to your PC using SteamLink without Meta Quest Link running at all (to do this, run Meta Quest Link app once on your PC, then exit the app from the taskbar icon. Now run Steam and SteamVR. When SteamVR asks if you want to set SteamVR as your default OpenXR runtime, just ignore it and leave it set as is). Also, make sure that "Hardware-accelerated GPU scheduling" is disabled in the Windows advanced graphics settings, otherwise SteamLink will keep randomly dropping the video stream. After TONS of experimentation with QuestLink, SteamVR and VirtualDesktop, I found that the above procedure gave beautiful performance in HalfLife Alyx, while other methods gave horrendous results.

I also found this thread about RTX 4070 not working with MetaQuestLink. As an alternative, you could use VirtualDesktop or SteamLink, both connect over wifi not via USB cable. VirtualDesktop costs a few dollars but is rather good and generally has better performance than SteamLink. But as noted above, SteamLink with MetaQuest's OpenXR runtime actually worked better for me with HalfLifeAlyx in this rare case.