You cannot. Using the phone as a monitor is not as easy as plugging in an HDMI cable to the dex dock and have data go in reversed.
There are some streaming solutions however you can use the device as secondary monitor and you will need a primary monitor still attach
Still can't use phone as webcam after more than 10 years, still cant use phone as display, we only just can use it as a pc, man progress is slow...
it is not about progress, it is about how the bus system of a device works. You cannot for example plug your phone into your pc and use it as a capture card, it is not how a capture card works.
A phone is suited for doing some stuff and other, you cannot expect it to do everything you want, and that is a fortune since something which can do everything means is something which also does it not in the best way possible.
By the way, what are you thinking to buy as a new monitor?
I've been saying since I'm 13 we should be able to use phones as camera, and as I grew older I said the same stuff about dashcams.
Due to covid some dashcams companies updated their software to be able to be used as webcam. This actually pissed me off, the fact they did what I ever wanted just because it would give their brand some attention.
This brings me back to the monitor, right now I'm in a complex situation, I can't move out and I'm stuck with a lease for another 4 months in an apartment with someone who's mentally ill and could potentially either murder me or break all my stuff (Without logical reason, last time was I forgot to turn the bathroom fan off... yeah... this kind of situation...). Knowing I can have my stuff on the fly is actually really important for me right now. I should be able to use my cellphone display just as easily as getting any data from the phone.
All devices should be versatile
oh shoot it is not a good situation at all.
The difference between using a dashcam as webcam and a smartphone as screen for a windows or macos device is the fact that due to how the stack of android works, and due to the way the bus of the device ect... is configured you cannot use a passthrough to the device screen simply by plugging it your pc, there is no physical way of doing that. The only thing you could do is streaming to your phone, however you need screen to stream to the device.
The difference is that if with dashcams the limitation was purely software to segment the market more in this case the impossibility to do that is purely hardware and software and is intrensice to the way the device works, you would need to profoundly change android security and low level processes and re project the bus as well as screen chip and soc architetcure to allow such a passthrough
Hopefully in the future then.
After all it's just a display and with some programming pretty sure it could be used with lightning, even if it has to change a lot.
But anyway, I'm pretty sure it'll be done, in how many years, I don't know...
I'm just tired of waiting.
If third party app like spacedesk and stuff like this exist and are that popular, there's a reason. I'm no the only one that wants this.
I've come across this website, that uses otg cable and hdmi adapter to convert mobile into a monitor.
hope it helps.
Timestamp quote https://youtu.be/PZLEUOG9k4Y?t=232
Latency shouldn't be an issue if the screen could be dedicated