I wouldn't say 0 delay because bluetooth always requires packing and unpacking the signal. But it's definitely usable compared to regular bluetooth.
I tested with a game installed on the Quest and the delay was barely noticeable.
I also tested Steam game. I used Steam Link wirelessly. My PC is connected to Wi-Fi so that might affect the latency but I noticed there was slightly more delay on Steam than on Quest game.
I didn't have chance yet to try wired connection on Steam so I can't say anything about that yet.
LE-audio on Quest is still said to be experimental so it might get better, closer to zero, but that remains to be seen. At least for me it's totally useable now.
Edit: I haven't tried Steam games with air link or virtual desktop yet. I will try to test air link this week how the latency compares to Steam link.
Edit 2: I tested with Air link both with wired and wireless. They both have similar slight delay when using Steam VR than with standalone Steam Link app on Quest glasses. So for Quest games the LE-audio is suitable. With Steam games I'm still doing some testing on my own when I have time if there's any settings to reduce it to similar levels than Quest games.
Edit 3: After tinkering with Steam VR a bit I think I found a solution that might work for me. When Steam VR is running, there's audio tab in settings where I can choose default output audio. I might buy cheap LE-audio dongle for PC where the earbuds connect when using Steam VR. That way I don't lose Quest audio when quitting Steam. Also the audio delay should be similar to Quest games because it comes straight from the source.
