Haven't tried the Apple Vision either but i do have a Quest 3 for a number of months now.
Never actually used it as a external monitor since i don't have a need for that functionality (I have plenty of desktop monitors around at home) apart from convenience of quickly able to go click a few things on a PC without pulling the headset off and grabbing a mouse and keyboard. My main use for it is VR gaming and it does a great job at it. This is what 90% of VR headset uses are for right now anyway (yet the Apple Vision has no support for games what so ever). Makes for a great sense of immersion with simulator type games without spending countless hours and dollars on a sim rig.
As for comfort... the Quest headsets are far from comfortable out of the box. You need to spend about 50$ extra in Chinese aftermarket accessories to get a better and much more comfortable way of attaching the headset to your head as well as fix some slight quality of life issues with it. After the aftermarket upgrades, then it is actually rather comfortable. The way the Apple Vision straps to the users head, it looks like it likely has similar comfort issues once used for >30 minutes.
Gaming in general tends to mask some of the issues, since there is enough stuff going on all the time that you might forget about comfort for a bit. This is not the case if you tried to use it as a serious productivity tool. Having physical controllers is also much superior to hand tracking. Sure hand tracking is cool and feels futuristic as heck when you first try it, but it pales to the super responsive and accurate tracking of controllers with IMU assistance, having buttons at your finger tips also makes UI interaction so much more versatile.