I know this is an old post, but I had this issue over the last few days. I still have Play Mode crashing using Oculus Link and Air Link. But here's what IS working: I purchased the Virtual Desktop app for Quest 2, and by default the Unity editor's play button will not trigger full screen VR, but the following forum post has instructions that worked for me with an admittedly hacky batch file to launch everything in the right order using the command line and specific command line argument(s). When I exit all programs, then use this Batch file, it will launch Virtual Desktop Streamer on my PC and wait for me to put the headset on and start the Virtual Desktop app on my Quest 2. Once the Virtual Desktop app on my Quest 2 connects to my PC, it will see the Unity editor which it has just launched. Then I can press Edit -> Play (for some reason the actual Play button still won't click) and it will enter Play Mode and correctly go fullscreen VR with spatialized audio, controllers, etc. I'm also using VRIF as the author of the post is, but I don't think that's related to why this is working. Best part of this is that it's completely wireless, no Link cable needed, and more performant than out-of-the-box Air Link in my experience. Here's the post URL: https://forum.unity.com/posts/6792485/
Of course, I hope that upcoming software updates will refine and stabilize the roundtrip workflow for Unity development, without the need for command line batch files and the third party Virtual Desktop app.