The Quest 2 already has passthrough. When you exit your guardian, which is an area you defined as "safe", it will use the external cameras to essentially act as thick glasses.
Not to say that it is some kind of blissful experience, but it works reasonably well to go get a glass of water.
It's getting there though. Vuzix have made really nice flat AR displays for their Blade. They just don't have a clue how to sell them afaik.