Basically the title, I want to use my laptop, which uses Arch Linux, and my tablet, which is an android one, as an external monitor for my desktop pc.
I believe you can buy a dummy HDMI plug and use Deskreen to host the screen in a webserver. This should work, but I don’t think it’s a good solution.
Edit: Deskreen seems to no longer be maintained and therefore doesn’t support wayland. I think it’s because of the Ukrainian war, and the creator being directly affected by it.
I did that from scratch a long while ago by creating a virtual x11 screen and vnc-ing to it from the tablet.
On some GPUs it works without a dummy plug.
There are some instructions out there, but I can’t search them (or my scripts) for you right now, sorry.
If you can’t manage to make it work, ping me again in a couple of days.
Quite sad actually, that you can’t just use laptop displays as external displays.