There's no precise criteria but the usual measure is ppd (pixels per degree) and it needs to be high enough such that detailed content (such as text) displayed at a reasonable size is clearly legible without eye strain.
> "Could you not just move your face closer to the virtual screen to see finer details?"
Sure, but then you have the problem of, say, using an IMAX screen as your computer monitor. The level of head motion required to consume screen content (i.e., a ton of large head movements) would make the device very uncomfortable quite quickly.
The Vision Pro has about ~35ppd and generally people seems to think it hits the bar for monitor replacement. Meta Quest 3 has ~25ppd and generally people seem to think it does not. The Steam Frame is specs-wise much closer to Quest 3 than Vision Pro.
There are some software things you can do to increase legibility of details like text, but ultimately you do need physical pixels.
> "Could you not just move your face closer to the virtual screen to see finer details?"
Sure, but then you have the problem of, say, using an IMAX screen as your computer monitor. The level of head motion required to consume screen content (i.e., a ton of large head movements) would make the device very uncomfortable quite quickly.
The Vision Pro has about ~35ppd and generally people seems to think it hits the bar for monitor replacement. Meta Quest 3 has ~25ppd and generally people seem to think it does not. The Steam Frame is specs-wise much closer to Quest 3 than Vision Pro.
There are some software things you can do to increase legibility of details like text, but ultimately you do need physical pixels.