Is there a way to force VLC to stream a second monitor when there isn't one?

So trick the PC into thinking there is a second monitor and then have VLC stream that one?

Then watch the stream on another device.
Please don't say "just buy a chromecast." They cost a lot here and would not be worth it for my use case. Also this much more a "can I?" than a "should I"

Linux? Have X make a new virtual screen.

A vnc server maybe? Chromecast is of limited usefulness because it's so locked down and underpowered (old ones can't even always play 720p youtube videos any more without horrible stutter), and the new ones are android TVs, which there are many other alternatives of.

There's also this interesting project if you want to repurpose an old x86 (apparently not too old as it needs SSE4.2) machine as an android tv https://xda-developers.com/android-...

do you know plex? It hosts your local movie files transcodes the video stream according to the recieving device screen resolution and bandwidth.

https://www.plex.tv
Watch Free Movies & TV | Stream Smarter ...

What's the other device?

Anything wifi based will be slow as shit and not worth the effort, although chromecasts do adjust for the lag.

Plex as @heyheni said can help but that depends on what's being streamed, (pre-recorded vs live stream)

Casting to a tablet, there's apps for that, but generally the response and lag is painful.

More details needed really to understand what your trying to achieve and why hardware you have lying around to do it with.

@heyheni I use plex for media but I need a way share the desktop and it has to be extended, not mirrored and miracast is not doing the trick

@C0D4 The primary device is a prehistoric laptop, hence miracast not working and the secondary device is raspberry pi

@TheBeardedOne ok.
So let me get this right.

Your trying to stream from your laptop, to your Rpi, and I'm assuming your Rpi is connected to a tv/monitor?

If this is the case, you might be able to get spacedesk to work for you.

Use the Rpi with the browser viewer.
And the server on your laptop.

https://spacedesk.net/

Sharing a whole screen probably won't give a decent performance for video playback unless you can accept low resolution. I would expect there to be delay, tearing, skipped frames, and/or compression artifacts. I would like to be proven wrong though.

If video playback is all you want, it's better to have something where the host machine doesn't do rendering, so no extended display.

@electrineer smooth is prefered but not required. It'll be for stuff like have documentation or a udemy course on the TV while I code on the laptop on the couch

So win+P then selecting extended allows me to pretend there's a second screen and I can stream through VLC but I can't get it to stream only the second screen